Table of contents

19 August 2022, Volume 31 Issue 9 Previous issue    Next issue

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GENERAL

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Characterizing entanglement in non-Hermitian chaotic systems via out-of-time ordered correlators Kai-Qian Huang(黄恺芊), Wei-Lin Li(李蔚琳), Wen-Lei Zhao(赵文垒), and Zhi Li(李志) Chin. Phys. B, 2022, 31 (9):  090301.  DOI: 10.1088/1674-1056/ac67c3 Abstract ( 436 )   HTML ( 0 )   PDF (544KB) ( 107 )   We investigate the quantum entanglement in a non-Hermitian kicking system. In the Hermitian case, the out-of-time ordered correlators (OTOCs) exhibit the unbounded power-law increase with time. Correspondingly, the linear entropy, which is a common measurement of entanglement, rapidly increases from zero to almost unity, indicating the formation of quantum entanglement. For strong enough non-Hermitian driving, both the OTOCs and linear entropy rapidly saturate as time evolves. Interestingly, with the increase of non-Hermitian kicking strength, the long-time averaged value of both OTOCs and linear entropy has the same transition point where they exhibit the sharp decrease from a plateau, demonstrating the disentanglment. We reveal the mechanism of disentanglement with the extension of Floquet theory to non-Hermitian systems.

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Steering quantum nonlocalities of quantum dot system suffering from decoherence Huan Yang(杨欢), Ling-Ling Xing(邢玲玲), Zhi-Yong Ding(丁智勇), Gang Zhang(张刚), and Liu Ye(叶柳) Chin. Phys. B, 2022, 31 (9):  090302.  DOI: 10.1088/1674-1056/ac615a Abstract ( 500 )   HTML ( 3 )   PDF (620KB) ( 253 )   The important applications of quantum dot system are to implement logic operations and achieve universal quantum computing based on different quantum nonlocalities. Here, we characterize the quantum steering, Bell nonlocality, and nonlocal advantage of quantum coherence (NAQC) of quantum dot system suffering nonunital and unital channels. The results reveal that quantum steering, Bell nonlocality, and NAQC can display the traits of dissipation, enhancement, and freezing. One can achieve the detections of quantum steering, Bell nonlocality, and NAQC of quantum dot system in different situations. Among these quantum nonlocalities, NAQC is the most fragile, and it is most easily influenced by different system parameters. Furthermore, considering quantum dot system coupling with amplitude damping channel and phase damping channel, these quantum nonlocalities degenerate with the enlargement of the channel parameters $t$ and $\varGamma$. Remarkably, measurement reversal can effectively control and enhance quantum steering, Bell nonlocality, and NAQC of quantum dot system suffering from decoherence, especially in the scenarios of the amplitude damping channel and strong operation strength.

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Probabilistic quantum teleportation of shared quantum secret Hengji Li(李恒吉), Jian Li(李剑), and Xiubo Chen(陈秀波) Chin. Phys. B, 2022, 31 (9):  090303.  DOI: 10.1088/1674-1056/ac67c0 Abstract ( 380 )   HTML ( 2 )   PDF (606KB) ( 79 )   Very recently, Lee et al. proposed a secure quantum teleportation protocol to transfer shared quantum secret between multiple parties in a network[Phys. Rev. Lett. 124 060501 (2020)]. This quantum network is encoded with a maximally entangled GHZ state. In this paper, we consider a partially entangled GHZ state as the entanglement channel, where it can achieve, probabilistically, unity fidelity transfer of the state. Two kinds of strategies are given. One arises when an auxiliary particle is introduced and a general evolution at any receiver's location is then adopted. The other one involves performing a single generalized Bell-state measurement at the location of any sender. This could allow the receivers to recover the transmitted state with a certain probability, in which only the local Pauli operators are performed, instead of introducing an auxiliary particle. In addition, the successful probability is provided, which is determined by the degree of entanglement of the partially multipartite entangled state. Moreover, the proposed protocol is robust against the bit and phase flip noise.

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Improvement of a continuous-variable measurement-device-independent quantum key distribution system via quantum scissors Lingzhi Kong(孔令志), Weiqi Liu(刘维琪), Fan Jing(荆凡), Zhe-Kun Zhang(张哲坤), Jin Qi(齐锦), and Chen He(贺晨) Chin. Phys. B, 2022, 31 (9):  090304.  DOI: 10.1088/1674-1056/ac6dba Abstract ( 430 )   HTML ( 6 )   PDF (1214KB) ( 207 )   We propose a new scheme to enhance the performance of the Gussian-modulated coherent-state continuous-variable measurement-device-independent quantum key distribution (CV-MDI-QKD) system via quantum scissors (QS) operation at Bob's side. As an non-deterministic amplifying setup, we firstly introduce the QS-enhanced CV-MDI-QKD protocol and then investigate the success probability of the QS operation in accordance with the equivalent one-way scheme. Afterwards, we investigate the effect of the QS operation on the proposed scheme and analyze the performance of the QS-enhanced CV-MDI-QKD system under the extreme asymmetric circumstance. Simulation results show that the QS operation can indeed improve the performance of the CV-MDI-QKD system considerably. QS-enhanced CV-MDI-QKD protocol outperforms the original CV-MDI-QKD protocol in both the maximum transmission distance and the secret key rate. Moreover, the better the performance of QS operation, the more significant the improvement of performance of the system.

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Spin-orbit coupling adjusting topological superfluid of mass-imbalanced Fermi gas Jian Feng(冯鉴), Wei-Wei Zhang(张伟伟), Liang-Wei Lin(林良伟), Qi-Peng Cai(蔡启鹏), Yi-Cai Zhang(张义财), Sheng-Can Ma(马胜灿), and Chao-Fei Liu(刘超飞) Chin. Phys. B, 2022, 31 (9):  090305.  DOI: 10.1088/1674-1056/ac6860 Abstract ( 378 )   HTML ( 1 )   PDF (3149KB) ( 86 )   Topological superfluid state is different from the normal superfluid one due to the excitation energy gap on the boundary. How to obtain the topological superfluid state by using spin-orbit coupling to control the s-waves paired mass-imbalanced Fermi gas is a recent novel topic. In this paper, we study the topological superfluid phase diagram of two-dimensional mass-imbalanced Fermi gas with Rashba spin-orbit coupling at zero temperature. We find that due to the competition among mass imbalance, pairing interaction and spin-orbit coupling, there is a double-well structure in the thermodynamic potential, which affects the properties of the ground state of the system. We comprehensively give the phase diagrams of the system on the plane of spin-orbit coupling and chemical potential, and the phase diagrams on the plane of the reduced mass ratio and two-body binding energy. This study not only points out the stable region of topological superfluid state of mass-imbalanced Fermi gas, but also provides a detailed theoretical basis for better observation of topological superfluid state in experiments.

TOPICAL REVIEW—Celebrating 30 Years of Chinese Physics B

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An overview of quantum error mitigation formulas Dayue Qin(秦大粤), Xiaosi Xu(徐晓思), and Ying Li(李颖) Chin. Phys. B, 2022, 31 (9):  090306.  DOI: 10.1088/1674-1056/ac7b1e Abstract ( 582 )   HTML ( 6 )   PDF (953KB) ( 612 )   Minimizing the effect of noise is essential for quantum computers. The conventional method to protect qubits against noise is through quantum error correction. However, for current quantum hardware in the so-called noisy intermediate-scale quantum (NISQ) era, noise presents in these systems and is too high for error correction to be beneficial. Quantum error mitigation is a set of alternative methods for minimizing errors, including error extrapolation, probabilistic error cancellation, measurement error mitigation, subspace expansion, symmetry verification, virtual distillation, etc. The requirement for these methods is usually less demanding than error correction. Quantum error mitigation is a promising way of reducing errors on NISQ quantum computers. This paper gives a comprehensive introduction to quantum error mitigation. The state-of-art error mitigation methods are covered and formulated in a general form, which provides a basis for comparing, combining and optimizing different methods in future work.

GENERAL

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High Chern number phase in topological insulator multilayer structures: A Dirac cone model study Yi-Xiang Wang(王义翔) and Fu-Xiang Li(李福祥) Chin. Phys. B, 2022, 31 (9):  090501.  DOI: 10.1088/1674-1056/ac6b2e Abstract ( 427 )   HTML ( 1 )   PDF (9060KB) ( 189 )   We employ the Dirac cone model to explore the high Chern number (C) phases that are realized in the magnetic-doped topological insulator (TI) multilayer structures by Zhao et al. [Nature 588 419 (2020)]. The Chern number is calculated by capturing the evolution of the phase boundaries with the parameters, then the Chern number phase diagrams of the TI multilayer structures are obtained. The high-C behavior is attributed to the band inversion of the renormalized Dirac cones, along with which the spin polarization at the $\varGamma$ point will get increased. Moreover, another two TI multilayer structures as well as the TI superlattice structures are studied.

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Improved functional-weight approach to oscillatory patterns in excitable networks Tao Li(李涛), Lin Yan(严霖), and Zhigang Zheng(郑志刚) Chin. Phys. B, 2022, 31 (9):  090502.  DOI: 10.1088/1674-1056/ac7458 Abstract ( 380 )   HTML ( 4 )   PDF (2090KB) ( 153 )   Studies of sustained oscillations on complex networks with excitable node dynamics received much interest in recent years. Although an individual unit is non-oscillatory, they may organize to form various collective oscillatory patterns through networked connections. An excitable network usually possesses a number of oscillatory modes dominated by different Winfree loops and numerous spatiotemporal patterns organized by different propagation path distributions. The traditional approach of the so-called dominant phase-advanced drive method has been well applied to the study of stationary oscillation patterns on a network. In this paper, we develop the functional-weight approach that has been successfully used in studies of sustained oscillations in gene-regulated networks by an extension to the high-dimensional node dynamics. This approach can be well applied to the study of sustained oscillations in coupled excitable units. We tested this scheme for different networks, such as homogeneous random networks, small-world networks, and scale-free networks and found it can accurately dig out the oscillation source and the propagation path. The present approach is believed to have the potential in studies competitive non-stationary dynamics.

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Effective sideband cooling in an ytterbium optical lattice clock Jin-Qi Wang(王进起), Ang Zhang(张昂), Cong-Cong Tian(田聪聪), Ni Yin(殷妮), Qiang Zhu(朱强), Bing Wang(王兵), Zhuan-Xian Xiong(熊转贤), Ling-Xiang He(贺凌翔), and Bao-Long Lv(吕宝龙) Chin. Phys. B, 2022, 31 (9):  090601.  DOI: 10.1088/1674-1056/ac5392 Abstract ( 408 )   HTML ( 2 )   PDF (898KB) ( 325 )   Sideband cooling is a key technique for improving the performance of optical atomic clocks by preparing cold atoms and single ions into the ground vibrational state. In this work, we demonstrate detailed experimental research on pulsed Raman sideband cooling in a $^{171}$Yb optical lattice clock. A sequence comprised of interleaved 578 nm cooling pulses resonant on the 1st-order red sideband and 1388 nm repumping pulses is carried out to transfer atoms into the motional ground state. We successfully decrease the axial temperature of atoms in the lattice from 6.5 μK to less than 0.8 μK in the trap depth of 24 μK, corresponding to an average axial motional quantum number $\langle n_z\rangle<0.03$. Rabi oscillation spectroscopy is measured to evaluate the effect of sideband cooling on inhomogeneous excitation. The maximum excitation fraction is increased from 0.8 to 0.86, indicating an enhancement in the quantum coherence of the ensemble. Our work will contribute to improving the instability and uncertainty of Yb lattice clocks.

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Spatially modulated scene illumination for intensity-compensated two-dimensional array photon-counting LiDAR imaging Jiaheng Xie(谢佳衡), Zijing Zhang(张子静)†, Mingwei Huang(黄明维),Jiahuan Li(李家欢), Fan Jia(贾凡), and Yuan Zhao(赵远)‡ Chin. Phys. B, 2022, 31 (9):  090701.  DOI: 10.1088/1674-1056/ac5e96 Abstract ( 382 )   HTML ( 4 )   PDF (9275KB) ( 104 )   Photon-counting LiDAR using a two-dimensional (2D) array detector has the advantages of high lateral resolution and fast acquisition speed. The non-uniform intensity profile of the illumination beam and non-uniform quantum efficiency of the detectors in the 2D array deteriorate the imaging quality. Herein, we propose a photon-counting LiDAR system that uses a spatial light modulator to control the spatial intensity to compensate for both the non-uniform intensity profile of the illumination beam, and the variation in the quantum efficiency of the detectors in the 2D array. By using a 635 nm peak wavelength and 4 mW average power semiconductor laser, lab-based experiments at a 4.27 m stand-off distance are performed to verify the effectiveness of the proposed method. Compared with the unmodulated method, the standard deviation of the intensity image of the proposed method is reduced from 0.109 to 0.089 for a whiteboard target, with an average signal photon number of 0.006 per pixel.

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Optoelectronic oscillator-based interrogation system for Michelson interferometric sensors Ling Liu(刘玲), Xiaoyan Wu(吴小龑), Guodong Liu(刘国栋), Tigang Ning(宁提纲),Jian Xu(许建), and Haidong You(油海东) Chin. Phys. B, 2022, 31 (9):  090702.  DOI: 10.1088/1674-1056/ac4f59 Abstract ( 372 )   HTML ( 0 )   PDF (868KB) ( 75 )   High-performance interrogation systems for optical fiber sensors are extensively required for environmental condition monitoring applications. In this article, we propose and demonstrate a Michelson interferometer (MI) interrogation system based on an optoelectronic oscillator (OEO). The frequency of the OEO is related to the free spectral range (FSR) of the MI. Thus, when the FSR of the MI varies with a change in external physical factors, the frequency of the OEO shifts and can be used for interrogation. We demonstrate that the temperature sensitivity and interrogation resolution are 35.35 MHz/℃ and 0.012 ℃, respectively. Such an OEO-based scheme enables wavelength-to-frequency mapping and promises a wide linear interrogation range, high resolution and high-speed interrogation.

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An all-optical phase detector by amplitude modulation of the local field in a Rydberg atom-based mixer Xiu-Bin Liu(刘修彬), Feng-Dong Jia(贾凤东), Huai-Yu Zhang(张怀宇), Jiong Mei(梅炅), Wei-Chen Liang(梁玮宸), Fei Zhou(周飞), Yong-Hong Yu(俞永宏), Ya Liu(刘娅), Jian Zhang(张剑), Feng Xie(谢锋), and Zhi-Ping Zhong(钟志萍) Chin. Phys. B, 2022, 31 (9):  090703.  DOI: 10.1088/1674-1056/ac6dbb Abstract ( 476 )   HTML ( 1 )   PDF (1664KB) ( 300 )   Recently, a Rydberg atom-based mixer was developed to measure the phase of a radio frequency (RF) field. The phase of the signal RF (SIG RF) field is down-converted directly to the phase of a beat signal created by the presence of a local RF (LO RF) field. In this study, we propose that the Rydberg atom-based mixer can be converted to an all-optical phase detector by amplitude modulation (AM) of the LO RF field; that is, the phase of the SIG RF field is related to both the amplitude and phase of the beat signal. When the AM frequency of the LO RF field is the same as the frequency of the beat signal, the beat signal will further interfere with the AM of the LO RF field inside the atom, and then the amplitude of the beat signal is related to the phase of the SIG RF field. The amplitude of the beat signal and the phase of the SIG RF field show a linear relationship within the range of 0 to π/2 when the phase of the AM is set with a difference π/4 from the phase of the LO RF field. The minimum phase resolution can be as small as 0.6° by optimizing the experimental conditions according to a simple theoretical model. This study will expand and contribute to the development of RF measurement devices based on Rydberg atoms.

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Real-time programmable coding metasurface antenna for multibeam switching and scanning Jia-Yu Yu(余佳宇), Qiu-Rong Zheng(郑秋容)†, Bin Zhang(张斌), Jie He(贺杰), Xiang-Ming Hu(胡湘明), and Jie Liu(刘杰) Chin. Phys. B, 2022, 31 (9):  090704.  DOI: 10.1088/1674-1056/ac80b2 Abstract ( 469 )   HTML ( 4 )   PDF (6301KB) ( 322 )   Novel electromagnetic wave modulation by programmable dynamic metasurface promotes the device design freedom, while multibeam antennas have sparked tremendous interest in wireless communications. A programmable coding antenna based on active metasurface elements (AMSEs) is proposed in this study, allowing scanning and state switching of multiple beams in real time. To obtain the planar array phase distribution in quick response, the aperture field superposition and discretization procedures are investigated. Without the need for a massive algorithm or elaborate design, this electronically controlled antenna with integrated radiation and phase-shift functions can flexibly manipulate the scattering state of multiple beams under field-programmable gate array (FPGA) control. Simulation and experimental results show that the multiple directional beams dynamically generated in the metasurface upper half space have good radiation performance, with the main lobe directions closely matching the predesigned angles. This metasurface antenna has great potential for future applications in multitarget radar, satellite navigation, and reconfigurable intelligent metasurfaces.

DATA PAPER

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Energy levels and magnetic dipole transition parameters for the nitrogen isoelectronic sequence Mu-Hong Hu(胡木宏), Nan Wang(王楠), Pin-Jun Ouyang(欧阳品均),Xin-Jie Feng(冯新杰), Yang Yang(杨扬), and Chen-Sheng Wu(武晨晟) Chin. Phys. B, 2022, 31 (9):  093101.  DOI: 10.1088/1674-1056/ac7a12 Abstract ( 459 )   HTML ( 7 )   PDF (905KB) ( 271 )   Theoretical calculations of the energy levels and magnetic dipole transition parameters for the 1s22s22p3 and 1s22p5 configurations of nitrogen isoelectronic sequence with Z=21-30 are performed using multi-congfiguration Dirac-Fock (MCDF) method. Based on the relativistic computational code GRASP2k compiled within the framework of MCDF method, the electron correlations, Breit interaction and QED effects are well treated in detail. The energy levels, line strengths and transition rates of magnetic dipole transition are obtained and compared with the experimental data available. For most cases, good agreements are achieved and the relative differences of them are less than 0.114%, 8.43% and 9.80%, respectively. The scaling laws of the fine structure splitting and transition rate are obtained on the isoelectronic sequence and the corresponding physical mechanisms are discussed. The data sets for tables are openly available at https://www.doi.org/10.57760/sciencedb.j00113.00022.

ATOMIC AND MOLECULAR PHYSICS

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New designed helical resonator to improve measurement accuracy of magic radio frequency Tian Guo(郭天), Peiliang Liu(刘培亮), and Chaohong Lee(李朝红) Chin. Phys. B, 2022, 31 (9):  093201.  DOI: 10.1088/1674-1056/ac6944 Abstract ( 370 )   HTML ( 3 )   PDF (1041KB) ( 138 )   Based upon the new designed helical resonator, the resonant radio frequency (RF) for trapping ions can be consecutively adjusted in a large range (about 12 MHz to 29 MHz) with high Q-factors (above 300). We analyze the helical resonator with a lumped element circuit model and find that the theoretical results fit well with the experimental data. With our resonator system, the resonant frequency near magic RF frequency (where the scalar Stark shift and the second-order Doppler shift due to excess micromotion cancel each other) can be continuously changed at kHz level. For 88Sr+ ion, compared to earlier results, the measurement accuracy of magic RF frequency can be improved by an order of magnitude upon rough calculation, and therefore the net micromotion frequency shifts can be further reduced. Also, the differential static scalar polarizability Δα0 of clock transition can be experimentally measured more accurately.

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Probing subcycle spectral structures and dynamics of high-order harmonic generation in crystals Long Lin(林龙), Tong-Gang Jia(贾铜钢), Zhi-Bin Wang(王志斌), and Peng-Cheng Li(李鹏程) Chin. Phys. B, 2022, 31 (9):  093202.  DOI: 10.1088/1674-1056/ac6943 Abstract ( 457 )   HTML ( 5 )   PDF (2913KB) ( 202 )   Subcycle spectral structures and dynamics of high-order harmonic generation (HHG) processes of atoms and molecules driven by intense laser fields on the attosecond time scale have been originally studied theoretically and experimentally. However, the time scale of HHG dynamics in crystals is in the order of sub-femtosecond, and the carrier dynamics of HHG in crystals driven by subcycle laser pulses are largely unexplored. Here we perform a theoretical study of subcycle structures, spectra, and dynamics of HHG of crystals in mid-infrared laser fields subject to excitation by a subcycle laser pulse with a time delay. The HHG spectra as a function of time delay between two laser fields are calculated by using a single-band model for the intra-band carrier dynamics in crystal momentum space and by solving the time-dependent Schrödinger equation in velocity gauge for the treatment of multi-band crystal systems. The results exhibit a complex time-delay-dependent oscillatory pattern, and the enhancement and suppression of the HHG related to subcycle pulse are observed at the given time delay in either single-band or multi-band crystal systems. To understand oscillation structures with respect to the dependence for the subcycle laser fields, the time-frequency characteristics of the HHG as well as the probability density distribution of the radiation are analyzed in detail.

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Spectroscopic study of B2Σ+–X1 2Π1/2 transition of electron electric dipole moment candidate PbF Ben Chen(陈犇), Yi-Ni Chen(陈旖旎), Jia-Nuan Pan(潘佳煖), Jian-Ping Yin(印建平), and Hai-Ling Wang(汪海玲)† Chin. Phys. B, 2022, 31 (9):  093301.  DOI: 10.1088/1674-1056/ac633a Abstract ( 444 )   HTML ( 4 )   PDF (1142KB) ( 96 )   PbF, a valuable candidate for measuring the electron electric dipole moment (eEDM), is of great significance in measuring its spectrum and deriving its molecular constants in experiment. In the present work, the rovibronic spectrum of the B$^{2}{\Sigma }^{+}$-X$_{1}^{\, 2}{\Pi }_{1/2}$ transition of PbF in a wavelength range of 260 nm-285 nm is studied by the laser ablation/laser induced fluorescence method. The molecular parameters of the X$_{1}^{\, 2}{\Pi }_{1/2}$ (${v''}=0)$ and B$^{2}{\Sigma }^{+}$ (${v}'=0, 1$) states are derived from the recorded spectra of the (0, 0) and (1, 0) bands of the B$^{2}{\Sigma }^{+}$-X$_{1}^{\, 2}{\Pi }_{1/2}$ transition. Also, the Franck-Condon factors (FCFs) of the transitions between the B$^{2}{\Sigma }^{+}$ and X$_{1}^{\, 2}{\Pi }_{1/2}$ states are calculated by the RKR/LEVEL method and the Morse potential method, respectively.

TOPICAL REVIEW—Celebrating 30 Years of Chinese Physics B

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Atomic structure and collision dynamics with highly charged ions Xinwen Ma(马新文), Shaofeng Zhang(张少锋), Weiqiang Wen(汶伟强), Zhongkui Huang(黄忠魁), Zhimin Hu(胡智民), Dalong Guo(郭大龙), Junwen Gao(高俊文), Bennaceur Najjari, Shenyue Xu(许慎跃), Shuncheng Yan(闫顺成), Ke Yao(姚科), Ruitian Zhang(张瑞田), Yong Gao(高永), and Xiaolong Zhu(朱小龙) Chin. Phys. B, 2022, 31 (9):  093401.  DOI: 10.1088/1674-1056/ac8736 Abstract ( 398 )   HTML ( 8 )   PDF (3242KB) ( 304 )   The research progresses on the investigations of atomic structure and collision dynamics with highly charged ions based on the heavy ion storage rings and electron ion beam traps in recent 20 years are reviewed. The structure part covers test of quantum electrodynamics and electron correlation in strong Coulomb field studied through dielectronic recombination spectroscopy and VUV/x-ray spectroscopy. The collision dynamics part includes charge exchange dynamics in ion-atom collisions mainly in Bohr velocity region, ion-induced fragmentation mechanisms of molecules, hydrogen-bound and van de Waals bound clusters, interference, and phase information observed in ion-atom/molecule collisions. With this achievements, two aspects of theoretical studies related to low energy and relativistic energy collisions are presented. The applications of data relevant to key atomic processes like dielectronic recombination and charge exchanges involving highly charged ions are discussed. At the end of this review, some future prospects of research related to highly charged ions are proposed.

ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS

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Dual-function terahertz metasurface based on vanadium dioxide and graphene Jiu-Sheng Li(李九生)† and Zhe-Wen Li(黎哲文) Chin. Phys. B, 2022, 31 (9):  094201.  DOI: 10.1088/1674-1056/ac5884 Abstract ( 437 )   HTML ( 3 )   PDF (2531KB) ( 230 )   A dual-function terahertz metasurface based on VO2 and graphene is proposed in this paper. It consists of a gold layer embedded with VO2 patches, a SiO2 spacer layer, a VO2 layer, graphene and a SiO2 spacer substrate. When the bottom VO2 layer is in the metallic state, the designed metasurface can achieve absorption. When the top VO2 patches are in the metallic state, the proposed metasurface can be used as a single-band absorber with terahertz absorptance of 99.7% at 0.736 THz. When the top VO2 patches are in the insulating state, the designed structure behaves as a dual-band absorber with an absorptance of 98.9% at 0.894 THz and 99.9% at 1.408 THz. In addition, the absorber is polarization insensitive and keeps good performance at large angles of incidence. When the bottom VO2 is in an insulating state, the metasurface shows electromagnetically induced transparency. The transparent window can be dynamically regulated by controlling the chemical potential of graphene. The proposed metasurface exhibits the advantages of terahertz absorption, electromagnetically induced transparency and dynamic control, which provides more options for the design of terahertz devices in the future.

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Deep-learning-based cryptanalysis of two types of nonlinear optical cryptosystems Xiao-Gang Wang(汪小刚) and Hao-Yu Wei(魏浩宇) Chin. Phys. B, 2022, 31 (9):  094202.  DOI: 10.1088/1674-1056/ac6331 Abstract ( 405 )   HTML ( 2 )   PDF (2402KB) ( 83 )   The two types of nonlinear optical cryptosystems (NOCs) that are respectively based on amplitude-phase retrieval algorithm (APRA) and phase retrieval algorithm (PRA) have attracted a lot of attention due to their unique mechanism of encryption process and remarkable ability to resist common attacks. In this paper, the securities of the two types of NOCs are evaluated by using a deep-learning (DL) method, where an end-to-end densely connected convolutional network (DenseNet) model for cryptanalysis is developed. The proposed DL-based method is able to retrieve unknown plaintexts from the given ciphertexts by using the trained DenseNet model without prior knowledge of any public or private key. The results of numerical experiments with the DenseNet model clearly demonstrate the validity and good performance of the proposed the DL-based attack on NOCs.

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Nonreciprocal coupling induced entanglement enhancement in a double-cavity optomechanical system Yuan-Yuan Liu(刘元元), Zhi-Ming Zhang(张智明), Jun-Hao Liu(刘军浩), Jin-Dong Wang(王金东), and Ya-Fei Yu(於亚飞) Chin. Phys. B, 2022, 31 (9):  094203.  DOI: 10.1088/1674-1056/ac6499 Abstract ( 424 )   HTML ( 1 )   PDF (1200KB) ( 123 )   We investigate the quantum entanglement in a double-cavity optomechanical system consisting of an optomechanical cavity and an auxiliary cavity, where the optomechanical cavity mode couples with the mechanical mode via radiation-pressure interaction, and simultaneously couples with the auxiliary cavity mode via nonreciprocal coupling. We study the entanglement between the mechanical oscillator and the cavity modes when the two cavities are reciprocally or nonreciprocally coupled. The logarithmic negativity $E_{n}^{(1)}$ ($E_{n}^{(2)}$) is adopted to describe the entanglement degree between the mechanical mode and the optomechanical cavity mode (the auxiliary cavity mode). We find that both $E_{n}^{(1)}$ and $E_{n}^{(2)}$ have maximum values in the case of reciprocal coupling. By using nonreciprocal coupling, $E_{n}^{(1)}$ and $E_{n}^{(2)}$ can exceed those maximum values, and a wider detuning region where the entanglement exists can be obtained. Moreover, the entanglement robustness with respect to the environment temperature is also effectively enhanced.

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Lateral characteristics improvements of DBR laser diode with tapered Bragg grating Qi-Qi Wang(王琦琦), Li Xu(徐莉)†, Jie Fan(范杰)‡, Hai-Zhu Wang(王海珠), and Xiao-Hui Ma(马晓辉) Chin. Phys. B, 2022, 31 (9):  094204.  DOI: 10.1088/1674-1056/ac6946 Abstract ( 402 )   HTML ( 0 )   PDF (2255KB) ( 41 )   Broad area semiconductor laser (BAL) has poor lateral beam quality due to lateral mode competition, which limits its application as a high-power optical source. In this work, the distributed Bragg reflector laser diode with tapered grating (TDBR-LD) is studied. By changing the lateral width, the tapered grating increases the loss of high-order lateral modes, thus improving the lateral characteristics of the laser diode. The measuring results show that the TDBR-LD can achieve a single-lobe output under 0.9 A. In contrast to the straight distributed Bragg reflector laser diode (SDBR-LD), the lateral far field divergence of TDBR-LD is measured to be 5.23° at 1 A, representing a 17% decline. The linewidth of TDBR-LD is 0.4 nm at 0.2 A, which is reduced by nearly 43% in comparison with that of SDBR-LD. Meanwhile, both of the devices have a maximum output power value of approximate 470 mW.

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Single-mode lasing in a coupled twin circular-side-octagon microcavity Ke Yang(杨珂), Yue-De Yang(杨跃德), Jin-Long Xiao(肖金龙), and Yong-Zhen Huang(黄永箴) Chin. Phys. B, 2022, 31 (9):  094205.  DOI: 10.1088/1674-1056/ac6802 Abstract ( 348 )   HTML ( 2 )   PDF (1670KB) ( 166 )   We demonstrate the curvature of coupled twin circular-side-octagon microcavity (TCOM) lasers as the degree of freedom to realize manipulation of mode quality ($Q$) factor and lasing characteristics. Numerical simulation results indicate that mode $Q$ factors varying from 10$^{4 }$ to 10$^{8}$, wavelength intervals of different transverse modes, and mode numbers for four-bounce modes can be manipulated for five different deformations. Global mode distributes throughout coupled microcavity with mode $Q$ factor around the order of 10$^{4 }$ or 10$^{5}$. Four-bounce modes lase with injection currents applied single microcavity. By pumping both microcavities simultaneously, single-mode lasing for global modes with side mode suppression ratios (SMSRs) of 30, 32, 32, 31, and 36 dB is achieved at the deformation of 0, 0.5, 1, 1.5, and 2 with four-bounce modes suppressed, respectively. Moreover, the linewidths less than 11 MHz for the single mode are obtained with the deformation of 2. The results show that the lasing modes can be efficiently manipulated considering variable curvature for TCOM lasers, which can promote practical applications of microcavity lasers.

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Numerical investigation of the nonlinear spectral broadening aiming at a few-cycle regime for 10 ps level Nd-doped lasers Xi-Hang Yang(杨西杭), Fen-Xiang Wu(吴分翔), Yi Xu(许毅), Jia-Bing Hu(胡家兵), Pei-Le Bai(白培乐), Hai-Dong Chen(陈海东), Xun Chen(陈洵), and Yu-Xin Leng(冷雨欣) Chin. Phys. B, 2022, 31 (9):  094206.  DOI: 10.1088/1674-1056/ac685e Abstract ( 542 )   HTML ( 3 )   PDF (2058KB) ( 233 )   We present a cascaded nonlinear spectral broadening scheme for Nd-doped lasers, featuring with long pulse duration and high average power. This scheme is based on two multi-pass cells (MPCs) and one multiple-plate supercontinuum generation (MPSG), and the numerical investigation is driven by a home-made Nd-doped fiber laser with 12 ps pulse duration, 50 kHz repetition rate and 100 W average power. The MPC-based first two stages allow us to broaden the pulse spectrum to 4 nm and 43 nm respectively, and subsequently, the MPSG-based third stage allows us to reach 235 nm spectral bandwidth. This broadened spectrum can support a Fourier-transfer-limited pulse duration of 9.8 fs, which is shorter than three optical cycles. To the best of our knowledge, it is the first time to demonstrate the possibility of few-cycle pulses generation based on the 10 ps level Nd-doped lasers. Such few-cycle and high average power laser sources should be attractive and prospective, benefiting from the characteristics of structure compact, low-cost and flexibility.

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High-sensitivity methane monitoring based on quasi-fundamental mode matched continuous-wave cavity ring-down spectroscopy Zhe Li(李哲), Shuang Yang(杨爽), Zhirong Zhang(张志荣), Hua Xia(夏滑), Tao Pang(庞涛),Bian Wu(吴边), Pengshuai Sun(孙鹏帅), Huadong Wang(王华东), and Runqing Yu(余润磬) Chin. Phys. B, 2022, 31 (9):  094207.  DOI: 10.1088/1674-1056/ac5d33 Abstract ( 391 )   HTML ( 3 )   PDF (3062KB) ( 102 )   Continuous-wave cavity ring-down spectroscopy (CW-CRDS) is an important technical means to monitor greenhouse gases in atmospheric environment. In this paper, a CW-CRDS system is built to meet the needs of atmospheric methane monitoring. The problem of mode matching is explained from the perspective of transverse mode and longitudinal mode, and the influence of laser injection efficiency on measurement precision is further analyzed. The results of cavity ring-down time measurement show that the measurement precision is higher when the laser is coupled with the fundamental mode. In the experiment, DFB laser is used to calibrate the system with standard methane concentration, and the measurement residual is less than ±4×10-4 μs-1. The methane concentration in the air is monitored in real time for two days. The results show the consistency of the concentration changes over the two days, which further demonstrates the reliability of the system for the measurement of trace methane. By analyzing the influence of mode matching, it not only assists the adjustment of the optical path, but also further improves the sensitivity of the system measurement.

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Temperature and strain sensitivities of surface and hybrid acoustic wave Brillouin scattering in optical microfibers Yi Liu(刘毅), Yuanqi Gu(顾源琦), Yu Ning(宁钰), Pengfei Chen(陈鹏飞), Yao Yao(姚尧),Yajun You(游亚军), Wenjun He(贺文君), and Xiujian Chou(丑修建) Chin. Phys. B, 2022, 31 (9):  094208.  DOI: 10.1088/1674-1056/ac5395 Abstract ( 412 )   HTML ( 0 )   PDF (1420KB) ( 133 )   Temperature and strain sensitivities of surface acoustic wave (SAW) and hybrid acoustic wave (HAW) Brillouin scattering (BS) in 1 μm-1.3 μm diameter optical microfibers are simulated. In contrast to stimulated Brillouin scattering (SBS) from bulk acoustic wave in standard optical fiber, SAW and HAW BS, due to SAWs and HAWs induced by the coupling of longitudinal and shear waves and propagating along the surface and core of microfiber respectively, facilitate innovative detection in optical microfibers sensing. The highest temperature and strain sensitivities of the hybrid acoustic modes (HAMs) are 1.082 MHz/℃ and 0.0289 MHz/με, respectively, which is suitable for microfiber sensing application of high temperature and strain resolutions. Meanwhile, the temperature and strain sensitivities of the SAMs are less affected by fiber diameter changes, ranging from 0.05 MHz/℃/μ to 0.25 MHz/℃/μ and 1×10-4 MHz/με/μ to 5×10-4 MHz/με/μ, respectively. It can be found that that SAW BS for temperature and strain sensing would put less stress on manufacturing constraints for optical microfibers. Besides, the simultaneous sensing of temperature and strain can be realized by SAW and HAW BS, with temperature and strain errors as low as 0.30 ℃-0.34 ℃ and 14.47 με-16.25 με.

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Second harmonic generation from precise diamond blade diced ridge waveguides Hui Xu(徐慧), Ziqi Li(李子琦), Chi Pang(逄驰), Rang Li(李让), Genglin Li(李庚霖), Sh. Akhmadaliev, Shengqiang Zhou(周生强), Qingming Lu(路庆明), Yuechen Jia(贾曰辰), and Feng Chen(陈峰) Chin. Phys. B, 2022, 31 (9):  094209.  DOI: 10.1088/1674-1056/ac5242 Abstract ( 423 )   HTML ( 2 )   PDF (2274KB) ( 96 )   Carbon ion irradiation and precise diamond blade dicing are applied to fabricate Nd:GdCOB ridge waveguides. The propagation properties of the fabricated Nd:GdCOB waveguides are investigated through experiments and theoretical analysis. Micro-Raman analysis reveals that the Nd:GdCOB crystal lattice expands during the irradiation process. Micro-second harmonic spectroscopic analysis suggests that the original nonlinear properties of the Nd:GdCOB crystal are greatly enhanced within the waveguide volume. Under pulsed 1064 nm laser pumping, second harmonic generation (SHG) at 532 nm has been achieved in the fabricated waveguides. The maximum SHG conversion efficiencies are determined to be ～ 8.32 %·W-1 and ～ 22.36 %·W-1 for planar and ridge waveguides, respectively.

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Bandwidth expansion and pulse shape optimized for 10 PW laser design via spectral shaping Da-Wei Li(李大为), Tao Wang(王韬), Xiao-Lei Yin(尹晓蕾), Li Wang(王利), Jia-Mei Li(李佳美),Hui Yu(余惠), Yong Cui(崔勇), Tian-Xiong Zhang(张天雄), Xing-Qiang Lu(卢兴强), and Guang Xu(徐光) Chin. Phys. B, 2022, 31 (9):  094210.  DOI: 10.1088/1674-1056/ac6018 Abstract ( 442 )   HTML ( 0 )   PDF (1049KB) ( 149 )   We demonstrated a scheme of bandwidth expansion and pulse shape optimized to afford 10 PW laser design via spectral shaping, which uses the existing Nd:glass amplifier chain of the SG PW laser. Compared to the amplified pulse with a gain-narrowing effect, the required parameters of injected pulse energy, spectral bandwidth, and shape are analyzed, together with their influence on the system B-integral, energy output capability, and temporal intensity contrast. A bandwidth expansion to 7 nm by using LiNbO3 birefringent spectral shaping resulted in an output energy of 2 kJ in a proof-of-principle experiment. The results are consistent with the theoretical prediction which suggests that the amplifier chain of SG PW laser is capable of achieving 6 kJ at the bandwidth of 7 nm and the B-integral < π . This will support a 10 PW laser with a compressed pulse energy of 4.8 kJ (efficiency=80%) at 480 fs.

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Wave mode computing method using the step-split Padé parabolic equation Chuan-Xiu Xu(徐传秀) and Guang-Ying Zheng(郑广赢) Chin. Phys. B, 2022, 31 (9):  094301.  DOI: 10.1088/1674-1056/ac6940 Abstract ( 463 )   HTML ( 1 )   PDF (4777KB) ( 199 )   Models based on a parabolic equation (PE) can accurately predict sound propagation problems in range-dependent ocean waveguides. Consequently, this method has developed rapidly in recent years. Compared with normal mode theory, PE focuses on numerical calculation, which is difficult to use in the mode domain analysis of sound propagation, such as the calculation of mode phase velocity and group velocity. To broaden the capability of PE models in analyzing the underwater sound field, a wave mode calculation method based on PE is proposed in this study. Step-split Padé PE recursive matrix equations are combined to obtain a propagation matrix. Then, the eigenvalue decomposition technique is applied to the matrix to extract sound mode eigenvalues and eigenfunctions. Numerical experiments on some typical waveguides are performed to test the accuracy and flexibility of the new method. Discussions on different orders of Padé approximant demonstrate angle limitations in PE and the missing root problem is also discussed to prove the advantage of the new method. The PE mode method can be expanded in the future to solve smooth wave modes in ocean waveguides, including fluctuating boundaries and sound speed profiles.

TOPICAL REVIEW—Celebrating 30 Years of Chinese Physics B

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Controlling acoustic orbital angular momentum with artificial structures: From physics to application Wei Wang(王未), Jingjing Liu(刘京京), Bin Liang (梁彬), and Jianchun Cheng(程建春) Chin. Phys. B, 2022, 31 (9):  094302.  DOI: 10.1088/1674-1056/ac7868 Abstract ( 466 )   HTML ( 7 )   PDF (11557KB) ( 391 )   Acoustic orbital angular momentum (OAM) associated with helicoidal wavefront recently attracts rapidly-growing attentions, offering a new degree of freedom for acoustic manipulation. Due to the unique dynamical behavior and inherent mode orthogonality of acoustic OAM, its harnessing is of fundamental interests for wave physics, with great potential in a plethora of applications. The recent advance in materials physics further boosts efforts into controlling OAM-carrying acoustic vortices, especially acoustic metasurfaces with planar profile and subwavelength thickness. Thanks to their unconventional acoustic properties beyond attainable in the nature, acoustic artificial structures provide a powerful platform for new research paradigm for efficient generation and diverse manipulation of OAM in ways not possible before, enabling novel applications in diverse scenarios ranging from underwater communication to object manipulation. In this article, we present a comprehensive view of this emerging field by delineating the fundamental physics of OAM-metasurface interaction and recent advances in the generation, manipulation, and application of acoustic OAM based on artificial structures, followed by an outlook for promising future directions and potential practical applications.

ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS

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A modified heuristics-based model for simulating realistic pedestrian movement behavior Wei-Li Wang(王维莉), Hai-Cheng Li(李海城), Jia-Yu Rong(戎加宇), Qin-Qin Fan(范勤勤), Xin Han(韩新), and Bei-Hua Cong(丛北华) Chin. Phys. B, 2022, 31 (9):  094501.  DOI: 10.1088/1674-1056/ac65f8 Abstract ( 402 )   HTML ( 1 )   PDF (4188KB) ( 115 )   Pedestrian movement simulation models are used in various areas, such as building evacuation, transportation engineering, and safety management of large events. It also provides effective means to uncover underlying mechanisms of collective behaviors. In this work, a modified heuristics-based model is presented. In this model, the potential collisions in the moving process are explicitly considered. Meanwhile, a series of simulations is conducted in two typical scenarios to demonstrate the influence of critical parameters on model performance. It is found that when facing a wide obstacle in a corridor, the larger the visual radius, the earlier the pedestrian starts to make a detour. In addition, when a pedestrian observes a large crowd walking toward him, he chooses to make a detour and moves in the flow in a uniform direction. Furthermore, the model can reproduce the lane formation pedestrian flow phenomena in relatively high-density situations. With the increase of pedestrian visual radius and the weight of potential collision resistance, more stable pedestrian lanes and fewer moving-through-the-counterflow pedestrians can be observed. In terms of model validation, the density-speed relationship of simulation results accords well with that of the published empirical data. Our results demonstrate that the modified heuristics-based model can overcome the deficiency of the original model, and reproduce more realistic pedestrian movement behavior.

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Exploring fundamental laws of classical mechanics via predicting the orbits of planets based on neural networks Jian Zhang(张健), Yiming Liu(刘一鸣), and Zhanchun Tu(涂展春) Chin. Phys. B, 2022, 31 (9):  094502.  DOI: 10.1088/1674-1056/ac8d88 Abstract ( 589 )   HTML ( 21 )   PDF (1058KB) ( 158 )   Neural networks have provided powerful approaches to solve various scientific problems. Many of them are even difficult for human experts who are good at accessing the physical laws from experimental data. We investigate whether neural networks can assist us in exploring the fundamental laws of classical mechanics from data of planetary motion. Firstly, we predict the orbits of planets in the geocentric system using the gate recurrent unit, one of the common neural networks. We find that the precision of the prediction is obviously improved when the information of the Sun is included in the training set. This result implies that the Sun is particularly important in the geocentric system without any prior knowledge, which inspires us to gain Copernicus' heliocentric theory. Secondly, we turn to the heliocentric system and make successfully mutual predictions between the position and velocity of planets. We hold that the successful prediction is due to the existence of enough conserved quantities (such as conservations of mechanical energy and angular momentum) in the system. Our research provides a new way to explore the existence of conserved quantities in mechanics system based on neural networks.

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Numerical simulation of the thermal non-equilibrium flow-field characteristics of a hypersonic Apollo-like vehicle Minghao Yu(喻明浩)†, Zeyang Qiu(邱泽洋), Bo Lv(吕博), and Zhe Wang(王哲) Chin. Phys. B, 2022, 31 (9):  094702.  DOI: 10.1088/1674-1056/ac6ed6 Abstract ( 484 )   HTML ( 0 )   PDF (7678KB) ( 146 )   In order to investigate the relationship between the flow-field parameters outside the vehicle and the altitude, this paper takes the Atmospheric Reentry Demonstrator (ARD) with an angle of attack of -20° as the research object and adopts a two-temperature model coupled with the shear-stress transport k-ω turbulence model to focus on the variation of flow-field parameters including flow-field pressure, Mach number and temperature with the reentry altitude. It is found that the flow-field high-pressure region and low-Mach region both appear in the shock layer near the head of the ARD, while the maximum pressure of the surface appears on the windward side of the ARD's head with a toroidal distribution, and the numerical magnitude is inversely proportional to the radius of the torus. With fluid through the shoulder of the ARD flow expansion plays a dominant role, the airflow velocity increases, the Mach number of the windward side of the rear cone increases and the flow-field pressure and surface pressure rapidly decrease. When the fluid passes through the shock layer, the translational-rotation temperature will increase before the vibration-electron temperature, there is a thermal non-equilibrium effect and the two temperatures will rapidly decrease again when approaching the surface of the ARD due to the existence of temperature gradient. At the same time, both the windward side of the shoulder and the back cover of the ARD suffer from a large thermal load and require thermal protection.

PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

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Parametric decay instabilities of lower hybrid waves on CFETR Taotao Zhou(周涛涛), Nong Xiang(项农), Chunyun Gan(甘春芸), Guozhang Jia(贾国章), and Jiale Chen(陈佳乐) Chin. Phys. B, 2022, 31 (9):  095201.  DOI: 10.1088/1674-1056/ac67c2 Abstract ( 422 )   HTML ( 0 )   PDF (986KB) ( 145 )   The lower hybrid current drive is a potential candidate for sustaining plasma current in tokamak steady-state operations, which could be used in China Fusion Engineering Test Reactor (CFETR) with input power up to a few tens of megawatts. Such high input power could trigger the well-known parametric instabilities (PIs) at the plasma edge affecting the propagation and absorption of the lower hybrid pump waves. By analytically solving the nonlinear dispersion relation describing PIs, an explicit expression of the PI growth rate is obtained and analyzed in detail. It is found that pressure is the key parameter determining the PI characteristics. Ion sound quasi-mode is the dominant decay channel in the low-pressure regime, while the ion cyclotron quasi-mode (ICQM), as well as its harmonics, becomes dominant in the intermediate regime. In the high-pressure regime, only one mixed channel is found, which is related to Landau damping by free-streaming ions. Analytical expressions of growth rates of these decay channels are also obtained to show the parameter dependence at different pressure limits. The above analytical results are used to estimate the PIs on a typical profile of CFETR, and verified by corresponding numerical calculations. ICQM is found to be the strongest decay channel with a considerable growth rate for CFETR.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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Migration of weakly bonded oxygen atoms in a-IGZO thin films and the positive shift of threshold voltage in TFTs Chen Wang(王琛), Wenmo Lu(路文墨), Fengnan Li(李奉南), Qiaomei Luo(罗巧梅), and Fei Ma(马飞)† Chin. Phys. B, 2022, 31 (9):  096101.  DOI: 10.1088/1674-1056/ac560f Abstract ( 396 )   HTML ( 1 )   PDF (5583KB) ( 195 )   Amorphous indium-gallium-zinc oxide (a-IGZO) thin films are prepared by pulsed laser deposition and fabricated into thin-film transistor (TFT) devices. In-situ x-ray photoelectron spectroscopy (XPS) illustrates that weakly bonded oxygen (O) atoms exist in a-IGZO thin films deposited at high O2 pressures, but these can be eliminated by vacuum annealing. The threshold voltage (Vth) of the a-IGZO TFTs is shifted under positive gate bias, and the Vth shift is positively related to the deposition pressure. A temperature variation experiment in the range of 20 K-300 K demonstrates that an activation energy of 144 meV is required for the Vth shift, which is close to the activation energy required for the migration of weakly bonded O atoms in a-IGZO thin films. Accordingly, the Vth shift is attributed to the acceptor-like states induced by the accumulation of weakly bonded O atoms at the a-IGZO/SiO2 interface under positive gate bias. These results provide an insight into the mechanism responsible for the Vth shift of the a-IGZO TFTs and help in the production of reliable designs.

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Microstructure and hardening effect of pure tungsten and ZrO2 strengthened tungsten under carbon ion irradiation at 700℃ Chun-Yang Luo(罗春阳), Bo Cui(崔博), Liu-Jie Xu(徐流杰), Le Zong(宗乐), Chuan Xu(徐川), En-Gang Fu(付恩刚), Xiao-Song Zhou(周晓松), Xing-Gui Long(龙兴贵), Shu-Ming Peng(彭述明), Shi-Zhong Wei(魏世忠), and Hua-Hai Shen(申华海) Chin. Phys. B, 2022, 31 (9):  096102.  DOI: 10.1088/1674-1056/ac6b25 Abstract ( 527 )   HTML ( 1 )   PDF (6200KB) ( 108 )   Microstructure evolution and hardening effect of pure tungsten and W-1.5%ZrO2 alloy under carbon ion irradiation are investigated by using transmission electron microscopy and nano-indentation. Carbon ion irradiation is performed at 700 ℃ with irradiation damages ranging from 0.25 dpa to 2.0 dpa. The results show that the irradiation defect clusters are mainly in the form of dislocation loop. The size and density of dislocation loops increase with irradiation damages intensifying. The W-1.5%ZrO2 alloy has a smaller dislocation loop size than that of pure tungsten. It is proposed that the phase boundaries have the ability to absorb and annihilate defects and the addition of ZrO2 phase improves the sink strength for irradiation defects. It is confirmed that the W-1.5%ZrO2 alloy shows a smaller change in hardness than the pure tungsten after being irradiated. From the above results, we conclude that the addition of ZrO2 into tungsten can significantly reduce the accumulation of irradiated defects and improve the irradiation resistance behaviors of the tungsten materials.

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Definition and expression of non-symmetric physical properties in space for uniaxial crystals Xiaojie Guo(郭晓杰), Lijuan Chen(陈丽娟), Zeliang Gao(高泽亮), Xin Yin(尹鑫), and Xutang Tao(陶绪堂) Chin. Phys. B, 2022, 31 (9):  096103.  DOI: 10.1088/1674-1056/ac4e09 Abstract ( 388 )   HTML ( 2 )   PDF (769KB) ( 28 )   The anisotropic physical property is the most noteworthy feature of crystals. In this paper, the subscript change method is used to analyze the sign changes of different tensors describing physical properties in uniaxial crystals. The distribution of some physical properties in special point groups exhibits non-symmetry in eight quadrants, which should attract the attention of crystal research. The difference between the crystallographic and physical coordinate systems and the lack of crystal symmetry operations are considered to be the origins of the non-symmetry. To avoid ambiguities and difficulties in characterizing and applying crystal physical properties, eight quadrants in space should be clarified. Hence, we proposed the use of piezoelectric properties to define the positive direction of the optical coordinate axis prior to the research and applications of optical properties.

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In situ study of calcite-III dimorphism using dynamic diamond anvil cell Xia Zhao(赵霞), Sheng-Hua Mei(梅升华), Zhi Zheng(郑直), Yue Gao(高悦), Jiang-Zhi Chen(陈姜智), Yue-Gao Liu(刘月高), Jian-Guo Sun(孙建国), Yan Li(李艳), and Jian-Hui Sun(孙建辉) Chin. Phys. B, 2022, 31 (9):  096201.  DOI: 10.1088/1674-1056/ac6157 Abstract ( 418 )   HTML ( 0 )   PDF (1343KB) ( 104 )   The phase transitions among the high-pressure polymorphic forms of CaCO3 (cc-I, cc-II, cc-III, and cc-IIIb) are investigated by dynamic diamond anvil cell (dDAC) and in situ Raman spectroscopy. Experiments are carried out at room temperature and high pressures up to 12.8 GPa with the pressurizing rate varying from 0.006 GPa/s to 0.056 GPa/s. In situ observation shows that with the increase of pressure, calcite transforms from cc-I to cc-II at ～ 1.5 GPa and from cc-II to cc-III at ～ 2.5 GPa, and transitions are independent of the pressurizing rate. Further, as the pressure continues to increase, the cc-IIIb begins to appear and coexists with cc-III within a pressure range that is inversely proportional to the pressurizing rate. At the pressurizing rates of 0.006, 0.012, 0.021, and 0.056 GPa/s, the coexistence pressure ranges of cc-III and cc-IIIb are 2.8 GPa-9.8 GPa, 3.1 GPa-6.9 GPa, 2.7 GPa-6.0 GPa, and 2.8 GPa-4.5 GPa, respectively. The dependence of the coexistence on the pressurizing rate may result from the influence of pressurizing rate on the activation process of transition by reducing the energy barrier. The higher the pressurizing rate, the lower the energy barrier is, and the easier it is to pull the system out of the coexistence state. The results of this in situ study provide new insights into the understanding of the phase transition of calcite.

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First-principles study on β-GeS monolayer as high performance electrode material for alkali metal ion batteries Meiqian Wan(万美茜), Zhongyong Zhang(张忠勇), Shangquan Zhao(赵尚泉)†, and Naigen Zhou(周耐根)‡ Chin. Phys. B, 2022, 31 (9):  096301.  DOI: 10.1088/1674-1056/ac5d2e Abstract ( 444 )   HTML ( 0 )   PDF (1835KB) ( 191 )   Based on the density functional theory calculations, we have investigated the feasibility of two-dimensional β-GeS monolayer as high-performance anodes for alkali metal ion batteries. The results show that the electrical conductivity of β-GeS monolayer can be enhanced after adsorbing the alkali metal atoms owing to the semiconductor-to-metal transition. The low diffusion barriers of alkali metal atoms on the β-GeS surface indicate a rapid charge/discharge rate without metal clustering. Moreover, the low average open-circuit voltage (0.211 V) and a high theoretical capacity (1024 mAh·g-1) for Na suggest that the β-GeS monolayer is a promising anode material for Na-ion batteries with high performance.

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Effect of spatial heterogeneity on level of rejuvenation in Ni80P20 metallic glass Tzu-Chia Chen, Mahyuddin KM Nasution, Abdullah Hasan Jabbar, Sarah Jawad Shoja, Waluyo Adi Siswanto, Sigiet Haryo Pranoto, Dmitry Bokov, Rustem Magizov, Yasser Fakri Mustafa, A. Surendar, Rustem Zalilov, Alexandr Sviderskiy, Alla Vorobeva, Dmitry Vorobyev, and Ahmed Alkhayyat Chin. Phys. B, 2022, 31 (9):  096401.  DOI: 10.1088/1674-1056/ac615e Abstract ( 422 )   HTML ( 1 )   PDF (7014KB) ( 96 )   Understanding the relation between spatial heterogeneity and structural rejuvenation is one of the hottest topics in the field of metallic glasses (MGs). In this work, molecular dynamics (MD) simulation is implemented to discover the effects of initial spatial heterogeneity on the level of rejuvenation in the Ni$_{80}$P$_{20 }$MGs. For this purpose, the samples are prepared with cooling rates of $10^{10}$ K/s-$10^{12}$ K/s to make glassy alloys with different atomic configurations. Firstly, it is found that the increase in the cooling rate leads the Gaussian-type shear modulus distribution to widen, indicating the aggregations in both elastically soft and hard regions. After the primary evaluations, the elastostatic loading is also used to transform structural rejuvenation into the atomic configurations. The results indicate that the sample with intermediate structural heterogeneity prepared with 10$^{11}$ K/s exhibits the maximum structural rejuvenation which is due to the fact that the atomic configuration in an intermediate structure contains more potential sites for generating the maximum atomic rearrangement and loosely packed regions under an external excitation. The features of atomic rearrangement and structural changes under the rejuvenation process are discussed in detail.

RAPID COMMUNICATION

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Selective formation of ultrathin PbSe on Ag(111) Jing Wang(王静), Meysam Bagheri Tagani, Li Zhang(张力), Yu Xia(夏雨), Qilong Wu(吴奇龙), Bo Li(黎博), Qiwei Tian(田麒玮), Yuan Tian(田园), Long-Jing Yin(殷隆晶), Lijie Zhang(张利杰), and Zhihui Qin(秦志辉) Chin. Phys. B, 2022, 31 (9):  096801.  DOI: 10.1088/1674-1056/ac7867 Abstract ( 479 )   HTML ( 5 )   PDF (3132KB) ( 373 )   Two-dimensional (2D) semiconductors, such as lead selenide (PbSe), locate at the key position of next-generation devices. However, the ultrathin PbSe is still rarely reported experimentally, particularly on metal substrates. Here, we report the ultrathin PbSe synthesized via sequential molecular beam epitaxy on Ag(111). The scanning tunneling microscopy is used to resolve the atomic structure and confirms the selective formation of ultrathin PbSe through the reaction between Ag5Se2 and Pb, as further evidenced by the theoretical calculation. It is also found that the increased accumulation of Pb leads to the improved quality of PbSe with larger and more uniform films. The detailed analysis demonstrates the bilayer structure of synthesized PbSe, which could be deemed to achieve the 2D limit. The differential conductance spectrum reveals a metallic feature of the PbSe film, indicating a certain interaction between PbSe and Ag(111). Moreover, the moiré pattern originated from the lattice mismatch between PbSe and Ag(111) is observed, and this moiré system provides the opportunity for studying physics under periodical modulation and for device applications. Our work illustrates a pathway to selectively synthesize ultrathin PbSe on metal surfaces and suggests a 2D experimental platform to explore PbSe-based opto-electronic and thermoelectric phenomena.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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In-plane optical anisotropy of two-dimensional VOCl single crystal with weak interlayer interaction Ruijie Wang(王瑞洁), Qilong Cui(崔其龙), Wen Zhu(朱文), Yijie Niu(牛艺杰), Zhanfeng Liu(刘站锋), Lei Zhang(张雷), Xiaojun Wu(武晓君), Shuangming Chen(陈双明), and Li Song(宋礼) Chin. Phys. B, 2022, 31 (9):  096802.  DOI: 10.1088/1674-1056/ac7555 Abstract ( 398 )   HTML ( 1 )   PDF (3530KB) ( 278 )   Transition-metal oxyhalides $MOX$ ($M = {\rm Fe}$, Cr, V; $O ={\rm oxygen}$, $X= {\rm F}$, Cl, Br, I), an emerging type of two-dimensional (2D) van der Waals materials, have been both theoretically and experimentally demonstrated to possess unique electronic and magnetic properties. However, the intrinsic in-plane anisotropic properties of 2D VOCl still lacks in-depth research, especially optical anisotropy. Herein, a systematic Raman spectroscopic study is performed on VOCl single-crystal with different incident laser polarization at various temperatures. The polarized-dependent Raman scattering spectra reveal that the ${{ A}}_{{\rm g}}$ mode of VOCl show a 2-lobed shape in parallel polarization configuration while a 4-lobed shape in vertical configuration. In addition, the temperature-dependent and thickness-dependent Raman scattering spectra confirm a relatively weak van der Waals interaction between each layers among VOCl single crystal. These findings might provide better understanding on the in-plane anisotropic phenomenon in VOCl layers, thus will accelate further application of 2D single crystals for nanoscale angle-dependent optoelectronics.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

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Theoretical study of M6X2 and M6XX' structure (M = Au, Ag; X,X' = S, Se): Electronic and optical properties, ability of photocatalytic water splitting, and tunable properties under biaxial strain Jiaqi Li(李嘉琪), Xinlu Cheng(程新路), and Hong Zhang(张红) Chin. Phys. B, 2022, 31 (9):  097101.  DOI: 10.1088/1674-1056/ac6580 Abstract ( 416 )   HTML ( 0 )   PDF (2463KB) ( 90 )   MoS$_{2}$, a transition metal dichalcogenide (TMDC), has attracted significant amount of attention due to its direct bandgap, tunability and optical properties. Recently, a novel structure consisting of MoS$_{2}$ and noble metal nanoclusters has been reported. Inspired by this, first principle calculations are implemented to predict the structures of $M_{6}X_{2}$ and $M_{6}XX'$ ($M= {\rm Au}$, Ag; $X$, $X' ={\rm S}$, Se). The calculated bandgap, band edge position, and optical absorption of these structures prove that the silver compounds (Ag$_{6}X_{2 }$ and Ag$_{6}XX'$) have great potential for catalytic water splitting. In addition, biaxial strain (tensile strain and compressive strain) is applied to adjust the properties of these materials. The bandgap presents a quasi-linear trend with the increase of the applied strain. Moreover, the transition between the direct and indirect bandgap is found. The outstanding electronic and optical properties of these materials provide strong evidence for their application in microelectronic devices, photoelectric devices, and photocatalytic materials.

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Large Seebeck coefficient resulting from chiral interactions in triangular triple quantum dots Yi-Ming Liu(刘一铭) and Jian-Hua Wei(魏建华) Chin. Phys. B, 2022, 31 (9):  097201.  DOI: 10.1088/1674-1056/ac6dae Abstract ( 444 )   HTML ( 0 )   PDF (934KB) ( 122 )   We theoretically study thermoelectric transport properties through a triangular triple-quantum-dot (TTQD) structure in the linear response regime using the hierarchical equations of motion approach. It is demonstrated that large Seebeck coefficient can be obtained when properly matching the interdot tunneling strength and magnetic flux at the electron-hole symmetry point, as a result of spin chiral interactions in the TTQD system. We present a systematic investigation of the thermopower (the Seebeck coefficient) dependence on the tunneling strength, magnetic flux, and on-site energy. The Seebeck coefficient shows a clear breakdown of electron-hole symmetry in the vicinity of the Kondo regime, accompanied by the deviation from the semiclassical Mott relation in the Kondo and mixed-valence regimes, which result from the many-body effects of the Kondo correlated induced resonance together with spin chiral interactions.

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Hexagonal boron phosphide and boron arsenide van der Waals heterostructure as high-efficiency solar cell Yi Li(李依), Dong Wei(魏东), Gaofu Guo(郭高甫), Gao Zhao(赵高), Yanan Tang(唐亚楠), and Xianqi Dai(戴宪起) Chin. Phys. B, 2022, 31 (9):  097301.  DOI: 10.1088/1674-1056/ac6b2a Abstract ( 383 )   HTML ( 2 )   PDF (4353KB) ( 246 )   The rapid development of two-dimensional (2D) materials offers new opportunities for 2D ultra-thin excitonic solar cells (XSCs). The construction of van der Waals heterostructure (vdWH) is a recognised and effective method of integrating the properties of single-layer 2D materials, creating particularly superior performance. Here, the prospects of h-BP/h-BAs vdW heterostructures in 2D excitonic solar cells are assessed. We systematically investigate the electronic properties and optical properties of heterogeneous structures by using the density functional theory (DFT) and first-principles calculations. The results indicate that the heterogeneous structure has good optoelectronic properties, such as a suitable direct bandgap and excellent optical absorption properties. The calculation of the phonon spectrum also confirms the well-defined kinetic stability of the heterstructure. We design the heterogeneous structure as a model for solar cells, and calculate its solar cell power conversion efficiency which reaches up to 16.51% and is higher than the highest efficiency reported in organic solar cells (11.7%). Our work illustrates the potential of h-BP/h-BAs heterostructure as a candidate for high-efficiency 2D excitonic solar cells.

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Current carrying states in the disordered quantum anomalous Hall effect Yi-Ming Dai(戴镒明), Si-Si Wang(王思思), Yan Yu(禹言), Ji-Huan Guan(关济寰), Hui-Hui Wang(王慧慧), and Yan-Yang Zhang(张艳阳) Chin. Phys. B, 2022, 31 (9):  097302.  DOI: 10.1088/1674-1056/ac5d2b Abstract ( 414 )   HTML ( 2 )   PDF (1561KB) ( 112 )   In a quantum Hall effect, flat Landau levels may be broadened by disorder. However, it has been found that in the thermodynamic limit, all extended (or current carrying) states shrink to one single energy value within each Landau level. On the other hand, a quantum anomalous Hall effect consists of dispersive bands with finite widths. We numerically investigate the picture of current carrying states in this case. With size scaling, the spectrum width of these states in each bulk band still shrinks to a single energy value in the thermodynamic limit, in a power law way. The magnitude of the scaling exponent at the intermediate disorder is close to that in the quantum Hall effects. The number of current carrying states obeys similar scaling rules, so that the density of states of current carrying states is finite. Other states in the bulk band are localized and may contribute to the formation of a topological Anderson insulator.

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Degradation and breakdown behaviors of SGTs under repetitive unclamped inductive switching avalanche stress Chenkai Zhu(朱晨凯), Linna Zhao(赵琳娜), Zhuo Yang(杨卓), and Xiaofeng Gu(顾晓峰) Chin. Phys. B, 2022, 31 (9):  097303.  DOI: 10.1088/1674-1056/ac615b Abstract ( 427 )   HTML ( 1 )   PDF (3307KB) ( 115 )   The repetitive unclamped inductive switching (UIS) avalanche stress is conducted to investigate the degradation and breakdown behaviors of conventional shield gate trench MOSFET (C-SGT) and P-ring SGT MOSFETs (P-SGT). It is found that the static and dynamic parameters of both devices show different degrees of degradation. Combining experimental and simulation results, the hot holes trapped into the Si/SiO2 interface and the increase of crystal lattice temperature should be responsible for the degradation and breakdown behaviors. Moreover, under repetitive UIS avalanche stress, the reliability of P-SGT overcomes that of C-SGT, benefitting from the decreasing of the impact ionization rate at bottom of field oxide caused by the existence of P-ring.

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Optical second-harmonic generation of Janus MoSSe monolayer Ce Bian(边策), Jianwei Shi(史建伟), Xinfeng Liu(刘新风), Yang Yang(杨洋), Haitao Yang(杨海涛), and Hongjun Gao(高鸿钧) Chin. Phys. B, 2022, 31 (9):  097304.  DOI: 10.1088/1674-1056/ac6db4 Abstract ( 634 )   HTML ( 7 )   PDF (1159KB) ( 343 )   The transition metal dichalcogenides (TMD) monolayers have shown strong second-harmonic generation (SHG) owing to their lack of inversion symmetry. These ultrathin layers then serve as the frequency converters that can be intergraded on a chip. Here, taking MoSSe as an example, we report the first detailed experimental study of the SHG of Janus TMD monolayer, in which the transition metal layer is sandwiched by the two distinct chalcogen layers. It is shown that the SHG effectively arises from an in-plane second-harmonic polarization under paraxial focusing and detection. Based on this, the orientation-resolved SHG spectroscopy is realized to readily determine the zigzag and armchair axes of the Janus crystal with an accuracy better than ±0.6°. Moreover, the SHG intensity is wavelength-dependent and can be greatly enhanced (～ 60 times) when the two-photon transition is resonant with the C-exciton state. Our findings uncover the SHG properties of Janus MoSSe monolayer, therefore lay the basis for its integrated frequency-doubling applications.

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Dynamic transport characteristics of side-coupled double-quantum-impurity systems Yi-Jie Wang(王一杰) and Jian-Hua Wei(魏建华) Chin. Phys. B, 2022, 31 (9):  097305.  DOI: 10.1088/1674-1056/ac6b1e Abstract ( 421 )   HTML ( 2 )   PDF (910KB) ( 127 )   A systematic study is performed on time-dependent dynamic transport characteristics of a side-coupled double-quantum-impurity system based on the hierarchical equations of motion. It is found that the transport current behaves like a single quantum dot when the coupling strength is low during tunneling or Coulomb coupling. For the case of only tunneling transition, the dynamic current oscillates due to the temporal coherence of the electron tunneling device. The oscillation frequency of the transport current is related to the step voltage applied by the lead, while temperature $T$, electron--electron interaction $U$ and the bandwidth $W$ have little influence. The amplitude of the current oscillation exists in positive correlation with $W$ and negative correlation with $U$. With the increase in coupling $t_{12}$ between impurities, the ground state of the system changes from a Kondo singlet of one impurity to a spin singlet of two impurities. Moreover, lowering the temperature could promote the Kondo effect to intensify the oscillation of the dynamic current. When only the Coulomb transition is coupled, it is found that the two split-off Hubbard peaks move upward and have different interference effects on the Kondo peak at the Fermi surface with the increase in $U_{12}$, from the dynamics point of view.

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On the Onsager-Casimir reciprocal relations in a tilted Weyl semimetal Hot! Bingyan Jiang(江丙炎), Jiaji Zhao(赵嘉佶), Lujunyu Wang(王陆君瑜), Ran Bi(毕然), Juewen Fan(范珏雯), Zhilin Li(李治林), and Xiaosong Wu(吴孝松) Chin. Phys. B, 2022, 31 (9):  097306.  DOI: 10.1088/1674-1056/ac754a Abstract ( 498 )   HTML ( 6 )   PDF (2042KB) ( 240 )   The Onsager-Casimir reciprocal relations are a fundamental symmetry of nonequilibrium statistical systems. Here we study an unusual chirality-dependent Hall effect in a tilted Weyl semimetal Co3Sn2S2 with broken time-reversal symmetry. It is confirmed that the reciprocal relations are satisfied. Since two Berry curvature effects, an anomalous velocity and a chiral chemical potential, contribute to the observed Hall effect, the reciprocal relations suggest their intriguing connection.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

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Impact of AlxGa1-xN barrier thickness and Al composition on electrical properties of ferroelectric HfZrO/Al2O3/AlGaN/GaN MFSHEMTs Yue Li(李跃), Xingpeng Liu(刘兴鹏), Tangyou Sun(孙堂友), Fabi Zhang(张法碧), Tao Fu(傅涛), Peihua Wang-yang(王阳培华), Haiou Li(李海鸥)†, and Yonghe Chen(陈永和)‡ Chin. Phys. B, 2022, 31 (9):  097307.  DOI: 10.1088/1674-1056/ac7b1a Abstract ( 490 )   HTML ( 1 )   PDF (1304KB) ( 185 )   Ferroelectric (FE) HfZrO/Al$_{2}$O$_{3}$ gate stack AlGaN/GaN metal-FE-semiconductor heterostructure high-electron mobility transistors (MFSHEMTs) with varying Al$_{x}$Ga$_{1-x}$N barrier thickness and Al composition are investigated and compared by TCAD simulation with non-FE HfO$_{2}$/Al$_{2}$O$_{3}$ gate stack metal-insulator-semiconductor heterostructure high-electron mobility transistors (MISHEMTs). Results show that the decrease of the two-dimensional electron gas (2DEG) density with decreasing AlGaN barrier thickness is more effectively suppressed in MFSHEMTs than that in MISHEMTs due to the enhanced FE polarization switching efficiency. The electrical characteristics of MFSHEMTs, including transconductance, subthreshold swing, and on-state current, effectively improve with decreasing AlGaN thickness in MFSHEMTs. High Al composition in AlGaN barrier layers that are under 3-nm thickness plays a great role in enhancing the 2DEG density and FE polarization in MFSHEMTs, improving the transconductance and the on-state current. The subthreshold swing and threshold voltage can be reduced by decreasing the AlGaN thickness and Al composition in MFSHEMTs, affording favorable conditions for further enhancing the device.

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Physical analysis of normally-off ALD Al2O3/GaN MOSFET with different substrates using self-terminating thermal oxidation-assisted wet etching technique Cheng-Yu Huang(黄成玉), Jin-Yan Wang(王金延), Bin Zhang(张斌), Zhen Fu(付振), Fang Liu(刘芳), Mao-Jun Wang(王茂俊), Meng-Jun Li(李梦军), Xin Wang(王鑫), Chen Wang(汪晨), Jia-Yin He(何佳音), and Yan-Dong He(何燕冬) Chin. Phys. B, 2022, 31 (9):  097401.  DOI: 10.1088/1674-1056/ac6743 Abstract ( 417 )   HTML ( 0 )   PDF (1088KB) ( 170 )   Based on the self-terminating thermal oxidation-assisted wet etching technique, two kinds of enhancement mode Al$_{2}$O$_{3}$/GaN MOSFETs (metal-oxide-semiconductor field-effect transistors) separately with sapphire substrate and Si substrate are prepared. It is found that the performance of sapphire substrate device is better than that of silicon substrate. Comparing these two devices, the maximum drain current of sapphire substrate device (401 mA/mm) is 1.76 times that of silicon substrate device (228 mA/mm), and the field-effect mobility ($\mu_{\rm FEmax}$) of sapphire substrate device (176 cm$^{2}$/V$\cdot$s) is 1.83 times that of silicon substrate device (96 cm$^{2}$/V$\cdot$s). The conductive resistance of silicon substrate device is 21.2 $\Omega {\cdot }$mm, while that of sapphire substrate device is only 15.2 $\Omega {\cdot }$mm, which is 61% that of silicon substrate device. The significant difference in performance between sapphire substrate and Si substrate is related to the differences in interface and border trap near Al$_{2}$O$_{3}$/GaN interface. Experimental studies show that (i) interface/border trap density in the sapphire substrate device is one order of magnitude lower than in the Si substrate device, (ii) Both the border traps in Al$_{2}$O$_{3}$ dielectric near Al$_{2}$O$_{3}$/GaN and the interface traps in Al$_{2}$O$_{3}$/GaN interface have a significantly effect on device channel mobility, and (iii) the properties of gallium nitride materials on different substrates are different due to wet etching. The research results in this work provide a reference for further optimizing the performances of silicon substrate devices.

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Anisotropic superconducting properties of FeSe0.5Te0.5 single crystals Jia-Ming Zhao(赵佳铭) and Zhi-He Wang(王智河) Chin. Phys. B, 2022, 31 (9):  097402.  DOI: 10.1088/1674-1056/ac5610 Abstract ( 381 )   HTML ( 2 )   PDF (4593KB) ( 174 )   We investigated the anisotropic electrical transport and magnetic properties of FeSe$_{0.5}$Te$_{0.5}$ single crystals grown by the self-flux method. The in-plane resistivity shows a metallic-like temperature dependence, while the out-of-plane resistivity shows a broad hump with a maximum at around 64 K. The magnetization loops for $H/\!/c$-axis and $H/\!/ab$-plane are also different, for example, there is a typical second peak for $H/\!/c$-axis. The in-plane critical current density is larger than the out-of-plane one. The coherence length and penetration depth were estimated by the Ginzburg-Landau theory. The anisotropic parameter $\gamma $ depends on the applied magnetic field and the temperature. The coupling of superconducting FeSe(Te) layers and the flux pinning mechanism relevant to anisotropy are also discussed.

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Josephson vortices and intrinsic Josephson junctions in the layered iron-based superconductor Ca10(Pt3As8)((Fe0.9Pt0.1)2As2)5 Hot! Qiang-Tao Sui(随强涛) and Xiang-Gang Qui(邱祥冈) Chin. Phys. B, 2022, 31 (9):  097403.  DOI: 10.1088/1674-1056/ac76ae Abstract ( 438 )   HTML ( 8 )   PDF (1517KB) ( 335 )   Modulated electronic state due to the layered crystal structures brings about moderate anisotropy of superconductivity in the iron-based superconductors and thus Abrikosov vortices are expected in the mixed state. However, based on the angular and temperature dependent transport measurements in iron-based superconductor Ca$_{10}$(Pt$_3$As$_8$)((Fe$_{0.9}$Pt$_{0.1}$)$_2$As$_2$)$_5$ with $T_{\rm c} \simeq 12$ K, we find clear evidences of a crossover from Abrikosov vortices to Josephson vortices at a crossover temperature $T^{\star} \simeq 7 $ K, when the applied magnetic field is parallel to the superconducting FeAs layers, i.e., the angle between the magnetic field and the FeAs layers $\theta = 0^\circ$. This crossover to Josephson vortices is demonstrated by an abnormal decrease (increase) of the critical current (flux-flow resistance) below $T^{\star}$, in contrast to the increase (decrease) of the critical current (flux-flow resistance) above $T^{\star}$ expected for Abrikosov vortices. Furthermore, when $\theta$ is larger than $0.5^\circ$, the flux-flow resistance and critical current have no anomalous behaviors across $T^{\star}$. These anomalous behaviors can be understood in terms of the distinct transition from the well-pinned Abrikosov vortices to the weakly-pinned Josephson vortices upon cooling, when the coherent length perpendicular to the FeAs layers $\xi_\bot$ becomes shorter than half of the interlayer distance $d/2$. These experimental findings indicate the existence of intrinsic Josephson junctions below $T^{\star}$ and thus quasi-two-dimensional superconductivity in Ca$_{10}$(Pt$_3$As$_8$)((Fe$_{0.9}$Pt$_{0.1}$)$_2$As$_2$)$_5$, similar to those in the cuprate superconductors.

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Finite superconducting square wire-network based on two-dimensional crystalline Mo2C Hot! Zhen Liu(刘震), Zi-Xuan Yang(杨子萱), Chuan Xu(徐川), Jia-Ji Zhao(赵嘉佶), Lu-Junyu Wang(王陆君瑜), Yun-Qi Fu(富云齐), Xue-Lei Liang(梁学磊), Hui-Ming Cheng(成会明), Wen-Cai Ren(任文才), Xiao-Song Wu(吴孝松), and Ning Kang(康宁) Chin. Phys. B, 2022, 31 (9):  097404.  DOI: 10.1088/1674-1056/ac67c7 Abstract ( 476 )   HTML ( 5 )   PDF (2372KB) ( 262 )   Superconducting wire-networks are paradigms to study Cooper pairing issues, vortex dynamics and arrangements. Recently, emergent low-dimensional crystalline superconductors were reported in the minimal-disorder limit, providing novel platforms to reveal vortices-related physics. Study on superconducting loops with high-crystallinity is thus currently demanded. Here, we report fabrication and transport measurement of finite square-network based on two-dimensional crystalline superconductor Mo2C. We observe oscillations in the resistance as a function of the magnetic flux through the loops. Resistance dips at both matching field and fractional fillings are revealed. Temperature and current evolutions are carried out in magnetoresistance to study vortex dynamics. The amplitude of oscillation is enhanced due to the interaction between thermally activated vortices and the currents induced in the loops. The driving current reduces the effective activation energy for vortex, giving rise to stronger vortex interaction. Moreover, by the thermally activated vortex creep model, we derive the effective potential barrier for vortex dissipation, which shows well-defined correspondence with structures in magnetoresistance. Our work shows that low-dimensional crystalline superconducting network based on Mo2C possesses pronounced potential in studying the modulation of vortex arrangements and dynamics, paving the way for further investigations on crystalline superconducting network with various configurations.

TOPICAL REVIEW—Celebrating 30 Years of Chinese Physics B

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Superconductivity and unconventional density waves in vanadium-based kagome materials AV3Sb5 Hui Chen(陈辉), Bin Hu(胡彬), Yuhan Ye(耶郁晗), Haitao Yang(杨海涛), and Hong-Jun Gao(高鸿钧) Chin. Phys. B, 2022, 31 (9):  097405.  DOI: 10.1088/1674-1056/ac7f95 Abstract ( 624 )   HTML ( 6 )   PDF (6290KB) ( 392 )   Recently, the discovery of vanadium-based kagome metal AV3Sb5 (A= K, Rb, Cs) has attracted great interest in the field of superconductivity due to the coexistence of superconductivity, non-trivial surface state and multiple density waves. In this topical review, we present recent works of superconductivity and unconventional density waves in vanadium-based kagome materials AV3Sb5. We start with the unconventional charge density waves, which are thought to correlate to the time-reversal symmetry-breaking orders and the unconventional anomalous Hall effects in AV3Sb5. Then we discuss the superconductivity and the topological band structure. Next, we review the competition between the superconductivity and charge density waves under different conditions of pressure, chemical doping, thickness, and strains. Finally, the experimental evidence of pseudogap pair density wave is discussed.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

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Influence of Dzyaloshinskii-Moriya interaction on the magnetic vortex reversal in an off-centered nanocontact geometry Hua-Nan Li(李化南), Tong-Xin Xue(薛彤鑫), Lei Chen(陈磊), Ying-Rui Sui(隋瑛瑞), and Mao-Bin Wei(魏茂彬)† Chin. Phys. B, 2022, 31 (9):  097501.  DOI: 10.1088/1674-1056/ac4cbd Abstract ( 399 )   HTML ( 0 )   PDF (1197KB) ( 233 )   The influence of Dzyaloshinskii-Moriya interaction (DMI) on the vortex reversal driven by an out-of-plane spin-polarized current in an off-centered nanocontact structure is investigated. The simulation results show that DMI plays a vital role in vortex core reversal, including reversal current density, reversal velocity and reversal time. Under the influence of DMI, magnetic vortices still reverse polarity through the nucleation and annihilation of vortex and anti-vortex, with some peculiar characteristics. These results open up new possibilities for the application of magnetic vortex-based spin-transfer encryption nano-storage.

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Strain-mediated magnetoelectric control of tunneling magnetoresistance in magnetic tunneling junction/ferroelectric hybrid structures Wenyu Huang(黄文宇), Cangmin Wang(王藏敏), Yichao Liu(刘艺超), Shaoting Wang(王绍庭), Weifeng Ge(葛威锋), Huaili Qiu(仇怀利), Yuanjun Yang(杨远俊), Ting Zhang(张霆), Hui Zhang(张汇), and Chen Gao(高琛) Chin. Phys. B, 2022, 31 (9):  097502.  DOI: 10.1088/1674-1056/ac523e Abstract ( 371 )   HTML ( 0 )   PDF (3830KB) ( 122 )   Because of the wide selectivity of ferromagnetic and ferroelectric (FE) components, electric-field (E-field) control of magnetism via strain mediation can be easily realized through composite multiferroic heterostructures. Here, an MgO-based magnetic tunnel junction (MTJ) is chosen rationally as the ferromagnetic constitution and a high-activity (001)-Pb(Mg$_{1/3}$Nb$_{2/3}$)$_{0.7}$Ti$_{0.3}$O$_{3}$ (PMN-0.3PT) single crystal is selected as the FE component to create a multiferroic MTJ/FE hybrid structure. The shape of tunneling magnetoresistance (TMR) versus in situ E-fields imprints the butterfly loop of the piezo-strain of the FE without magnetic-field bias. The E-field-controlled change in the TMR ratio is up to $-$0.27% without magnetic-field bias. Moreover, when a typical magnetic field ($\sim \pm 10$ Oe) is applied along the minor axis of the MTJ, the butterfly loop is changed significantly by the E-fields relative to that without magnetic-field bias. This suggests that the E-field-controlled junction resistance is spin-dependent and correlated with magnetization switching in the free layer of the MTJ. In addition, based on such a multiferroic heterostructure, a strain-gauge factor up to approximately 40 is achieved, which decreases further with a sign change from positive to negative with increasing magnetic fields. This multiferroic hybrid structure is a promising avenue to control TMR through E-fields in low-power-consumption spintronic and straintronic devices at room temperature.

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Slight Co-doping tuned magnetic and electric properties on cubic BaFeO3 single crystal Hot! Shijun Qin(覃湜俊), Bowen Zhou(周博文), Zhehong Liu(刘哲宏), Xubin Ye(叶旭斌), Xueqiang Zhang(张雪强), Zhao Pan(潘昭), and Youwen Long(龙有文) Chin. Phys. B, 2022, 31 (9):  097503.  DOI: 10.1088/1674-1056/ac7549 Abstract ( 661 )   HTML ( 23 )   PDF (2095KB) ( 453 )   The single crystal of cubic perovskite BaFeO$_{3}$ shows multiple magnetic transitions and external stimulus sensitive magnetism. In this paper, a 5%-Co-doped BaFeO$_{3}$ (i.e. BaFe$_{0.95}$Co$_{0.05}$O$_{3})$ single crystal was grown by combining floating zone methods with high-pressure techniques. Such a slight Co doping has little effect on crystal structure, but significantly changes the magnetism from the parent antiferromagnetic ground state to a ferromagnetic one with the Curie temperature $T_{\rm C} \approx 120$ K. Compared with the parent BaFeO$_{3}$ at the induced ferromagnetic state, the saturated magnetic moment of the doped BaFe$_{0.95}$Co$_{0.05}$O$_{3}$ increases by about 10% and reaches 3.64 $\mu_{\rm B}$/f.u. Resistivity and specific heat measurements show that the ferromagnetic ordering favors metallic-like electrical transport behavior for BaFe$_{0.95}$Co$_{0.05}$O$_{3}$. The present work indicates that Co-doping is an effective method to tune the magnetic and electric properties for the cubic perovskite phase of BaFeO$_{3}$.

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Enhancement of spin-orbit torque efficiency by tailoring interfacial spin-orbit coupling in Pt-based magnetic multilayers Hot! Wenqiang Wang(王文强), Gengkuan Zhu(朱耿宽), Kaiyuan Zhou(周恺元), Xiang Zhan(战翔), Zui Tao(陶醉), Qingwei Fu(付清为), Like Liang(梁力克), Zishuang Li(李子爽), Lina Chen(陈丽娜), Chunjie Yan(晏春杰), Haotian Li(李浩天), Tiejun Zhou(周铁军), and Ronghua Liu(刘荣华) Chin. Phys. B, 2022, 31 (9):  097504.  DOI: 10.1088/1674-1056/ac76aa Abstract ( 488 )   HTML ( 7 )   PDF (1342KB) ( 246 )   We study inserting Co layer thickness-dependent spin transport and spin-orbit torques (SOTs) in the Pt/Co/Py trilayers by spin-torque ferromagnetic resonance. The interfacial perpendicular magnetic anisotropy (IPMA) energy density ($K_{\rm s}= 2.7 $ erg/cm$^{2}$, 1 erg = 10$^{-7}$ J), which is dominated by interfacial spin-orbit coupling (ISOC) in the Pt/Co interface, total effective spin-mixing conductance $(G_{\mathrm{eff,tot}}^{\mathrm{\uparrow \downarrow }}=\mathrm{0.42\times }{10}^{15} \mathrm{\Omega }^{-1}\cdot\mathrm{m}^{-2}$) and two-magnon scattering ($\beta_{\mathrm{TMS}}= 0.46 {\mathrm{nm}}^{2}$) are first characterized, and the damping-like torque ($\xi_{\mathrm{DL}}= 0.103$) and field-like torque ($\xi _{\mathrm{FL}}=-0.017$) efficiencies are also calculated quantitatively by varying the thickness of the inserting Co layer. The significant enhancement of $\xi_{\mathrm{DL}}$ and $\xi_{\mathrm{FL}}$ in Pt/Co/Py than Pt/Py bilayer system originates from the interfacial Rashba-Edelstein effect due to the strong ISOC between Co-3d and Pt-5d orbitals at the Pt/Co interface. Additionally, we find a considerable out-of-plane spin polarization SOT, which is ascribed to the spin anomalous Hall effect and possible spin precession effect due to IPMA-induced perpendicular magnetization at the Pt/Co interface. Our results demonstrate that the ISOC of the Pt/Co interface plays a vital role in spin transport and SOTs-generation. Our finds offer an alternative approach to improve the conventional SOTs efficiencies and generate unconventional SOTs with out-of-plane spin polarization to develop low power Pt-based spintronic via tailoring the Pt/FM interface.

TOPICAL REVIEW—Celebrating 30 Years of Chinese Physics B

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Computational studies on magnetism and ferroelectricity Ke Xu(徐可), Junsheng Feng(冯俊生), and Hongjun Xiang(向红军) Chin. Phys. B, 2022, 31 (9):  097505.  DOI: 10.1088/1674-1056/ac7b1b Abstract ( 476 )   HTML ( 7 )   PDF (2190KB) ( 325 )   Magnetics, ferroelectrics, and multiferroics have attracted great attentions because they are not only extremely important for investigating fundamental physics, but also have important applications in information technology. Here, recent computational studies on magnetism and ferroelectricity are reviewed. We first give a brief introduction to magnets, ferroelectrics, and multiferroics. Then, theoretical models and corresponding computational methods for investigating these materials are presented. In particular, a new method for computing the linear magnetoelectric coupling tensor without applying an external field in the first principle calculations is proposed for the first time. The functionalities of our home-made Property Analysis and Simulation Package for materials (PASP) and its applications in the field of magnetism and ferroelectricity are discussed. Finally, we summarize this review and give a perspective on possible directions of future computational studies on magnetism and ferroelectricity.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

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Efficiently enhanced energy storage performance of Ba2Bi4Ti5O18 film by co-doping Fe3+ and Ta5+ ion with larger radius Qiong Wu(吴琼), Lei Zhao(赵雷), Xinghao Chen(陈兴豪), and Shifeng Zhao(赵世峰)† Chin. Phys. B, 2022, 31 (9):  097701.  DOI: 10.1088/1674-1056/ac5393 Abstract ( 438 )   HTML ( 0 )   PDF (1069KB) ( 92 )   We present an efficient strategy, that is the co-substitution of Fe3+ and Ta5+ ions with large radius for Ti4+ ion, to enhance energy storage performance of Ba2Bi4Ti5O18 film. For the films co-doped with Fe3+ and Ta5+ ions, the maximum polarization under the same external electric field is improved because the radius of Fe3+ and Ta5+ ions is larger than that of Ti4+ ion. Moreover, due to the composition and chemical disorder, the relaxor properties are also slightly improved, which can not be achieved by the film doped with Fe3+ ions only. What is more, for the films doped with Fe3+ ion only, the leakage current density increases greatly due to the charge imbalance, resulting in a significant decrease in breakdown strength. It is worth mentioning that the breakdown strength of Fe3+ and Ta5+ ions co-doped film does not decrease due to the charge balance. Another important point is the recoverable energy storage density of the films co-doped with Fe3+ and Ta5+ ions has been greatly improved based on the fact that the maximum external electric field does not decrease and the maximum polarization under the same external electric field increases. On top of that, the hysteresis of the polarization has also been improved. Finally, the co-doped films with Fe3+ and Ta5+ ions have good frequency and temperature stability.

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Measurement of CO, HCN, and NO productions in atmospheric reaction induced by femtosecond laser filament Xiao-Dong Huang(黄晓东), Meng Zhang(张梦), Lun-Hua Deng(邓伦华), Shan-Biao Pang(庞山彪), Ke Liu(刘珂), and Huai-Liang Xu(徐淮良) Chin. Phys. B, 2022, 31 (9):  097801.  DOI: 10.1088/1674-1056/ac6b28 Abstract ( 400 )   HTML ( 0 )   PDF (1175KB) ( 118 )   It is proved that the chemical reaction induced by femtosecond laser filament in the atmosphere produces CO, HCN, and NO, and the production CO and HCN are observed for the first time. The concentrations of the products are measured by mid-infrared tunable laser absorption spectroscopy. In the reduced pressure air, the decomposition of CO2 is enhanced by vibration excitation induced by laser filament, resulting in the enhanced production of CO and HCN. At the same time, the CO and HCN generated from the atmosphere suffer rotation excitation induced by laser filament, enhancing their absorption spectra. It is found that NO, CO, and HCN accumulate to 134 ppm, 80 ppm, and 1.6 ppm in sealed air after sufficient reaction time. The atmospheric chemical reaction induced by laser filament opens the way to changing the air composition while maintaining environmental benefits.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

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Gamma induced changes in Makrofol/CdSe nanocomposite films Ali A. Alhazime, M. ME. Barakat, Radiyah A. Bahareth, E. M. Mahrous,Saad Aldawood, S. Abd El Aal, and S. A. Nouh Chin. Phys. B, 2022, 31 (9):  097802.  DOI: 10.1088/1674-1056/ac4909 Abstract ( 341 )   HTML ( 0 )   PDF (1694KB) ( 124 )   We applied an ex-situ casting procedure to prepare a nanocomposite (NCP) from Makrofol polycarbonate (PC) and CdSe nanoparticles. The CdSe nanoparticles were prepared by a thermolysis procedure in the presence of N2 gas flow. Rietveld refinement of x-ray data illustrated that the CdSe adopts a cubic zinc blend structure of 6.057 Å lattice parameter and 2 nm typical grain size. Samples from the prepared NCP were exposed to γ dosages (20 kGy-250 kGy). The modifications induced in the NCP films owing to γ dosages have been studied. The γ irradiation (50 kGy-250 kGy) causes crosslinks that reduce the optical bandgap from 4.15 eV to 3.81 eV, associated with an increase in dielectric parameters and refractive index. This is attributed to an increase in the mass fraction of the disordered regions as specified by x-ray diffraction. The PC-CdSe NCP was found to have a reaction to color modification which makes it suitable for saleable reproduction on a printing press.

TOPICAL REVIEW—Celebrating 30 Years of Chinese Physics B

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Hydrodynamic metamaterials for flow manipulation: Functions and prospects Bin Wang(王斌) and Jiping Huang (黄吉平) Chin. Phys. B, 2022, 31 (9):  098101.  DOI: 10.1088/1674-1056/ac7f8c Abstract ( 493 )   HTML ( 1 )   PDF (5381KB) ( 310 )   As an emerging branch in the area of flow control, hydrodynamic metamaterials have received considerable attention because of their novel flow control capabilities. In this review, we present prominent studies on hydrodynamic metamaterials in porous media, non-porous media, creeping flows, and non-creeping flows from several perspectives. In particular, for hydrodynamic cloaking metamaterials, we unify the descriptive form of transformation hydrodynamics for hydrodynamic metamaterials in porous and non-porous media by the hydrodynamic governing equations. Finally, we summarize and outlook the current shortcomings and challenges of current hydrodynamic metamaterials and propose possible future research directions, especially for microfluidics, exotic fluids, hydrodynamic cloaking in high Reynolds numbers, and turbulence.

INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY

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Transmissive 2-bit anisotropic coding metasurface Pengtao Lai(来鹏涛), Zenglin Li(李增霖), Wei Wang(王炜), Jia Qu(曲嘉), Liangwei Wu(吴良威),Tingting Lv(吕婷婷), Bo Lv(吕博), Zheng Zhu(朱正), Yuxiang Li(李玉祥),Chunying Guan(关春颖), Huifeng Ma(马慧锋), and Jinhui Shi(史金辉) Chin. Phys. B, 2022, 31 (9):  098102.  DOI: 10.1088/1674-1056/ac4a6b Abstract ( 588 )   HTML ( 1 )   PDF (2420KB) ( 144 )   Coding metasurfaces have attracted tremendous interests due to unique capabilities of manipulating electromagnetic wave. However, archiving transmissive coding metasurface is still challenging. Here we propose a transmissive anisotropic coding metasurface that enables the independent control of two orthogonal polarizations. The polarization beam splitter and the orbital angular momentum (OAM) generator have been studied as typical applications of the anisotropic 2-bit coding metasurface. The simulated far field patterns illustrate that the x and y polarized electromagnetic waves are deflected into two different directions, respectively. The anisotropic coding metasurface has been experimentally verified to realize an OAM beam with l = 2 of right-handed polarized wave, resulting from both contributions from linear-to-circular polarization conversion and the phase profile modulation. This work is beneficial to enrich the polarization manipulation field and develop transmissive coding metasurfaces.

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High-quality CdS quantum dots sensitized ZnO nanotube array films for superior photoelectrochemical performance Qian-Qian Gong(宫倩倩), Yun-Long Zhao(赵云龙), Qi Zhang(张奇), Chun-Yong Hu(胡春永), Teng-Fei Liu(刘腾飞), Hai-Feng Zhang(张海峰), Guang-Chao Yin(尹广超)†, and Mei-Ling Sun(孙美玲)‡ Chin. Phys. B, 2022, 31 (9):  098103.  DOI: 10.1088/1674-1056/ac4cc2 Abstract ( 407 )   HTML ( 0 )   PDF (3948KB) ( 61 )   The surface characteristics of ZnO were synthetically optimized by a self-designed simultaneous etching and W-doping hydrothermal method utilizing as-prepared ZnO nanorod (NR) array films as the template. Benefiting from the etching and regrowth process and the different structural stabilities of the various faces of ZnO NRs, the uniquely etched and W-doped ZnO (EWZ) nanotube (NT) array films with larger surface area, more active sites and better energy band structure were used to improve the photoelectrochemical (PEC) performance and the loading quality of CdS quantum dots (QDs). On the basis of their better surface characteristics, the CdS QDs were uniformly loaded on EWZ NT array film with a good coverage ratio and interface connection; this effectively improved the light-harvesting ability, charge transportation and separation as well as charge injection efficiency during the PEC reaction. Therefore, all the CdS QD-sensitized EWZ NT array films exhibited significantly enhanced PEC performance. The CdS/EWZ-7 composite films exhibited the optimal photocurrent density with a value of 12 mA· cm-2, 2.5 times higher than that of conventional CdS/ZnO-7 composite films under the same sensitization times with CdS QDs. The corresponding etching and optimizing mechanisms were also discussed.

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Broadband chirped InAs quantum-dot superluminescent diodes with a small spectral dip of 0.2 dB Hong Wang(王虹), Zunren Lv(吕尊仁), Shuai Wang(汪帅), Haomiao Wang(王浩淼), Hongyu Chai(柴宏宇), Xiaoguang Yang(杨晓光), Lei Meng(孟磊), Chen Ji(吉晨), and Tao Yang(杨涛) Chin. Phys. B, 2022, 31 (9):  098104.  DOI: 10.1088/1674-1056/ac657f Abstract ( 469 )   HTML ( 0 )   PDF (949KB) ( 57 )   We report on the fabrication and characterization of InAs/GaAs chirped multilayer quantum-dot superluminescent diodes (CMQD-SLDs) with and without direct Si doping in QDs. It was found that both the output power and the spectral width of the CMQD-SLDs were significantly enhanced by direct Si doping in the QDs. The output power and spectral width have been increased by approximately 18.3% and 40%, respectively. Moreover, we shortened the cavity length of the doped CMQD-SLD and obtained a spectral width of 106 nm. In addition, the maximum output power and spectral width of the CMQD-SLD doped directly with Si can be further increased to 16.6 mW and 114 nm, respectively, through anti-reflection coating and device packaging. The device exhibited the smallest spectral dip of 0.2 dB when the spectrum was widest. The improved performances of the doped CMQD-SLD can be attributed to the direct doping of Si in the QDs, optimization of device structure and device packaging.

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Numerical simulation on dendritic growth of Al-Cu alloy under convection based on the cellular automaton lattice Boltzmann method Kang-Wei Wang(王康伟), Meng-Wu Wu(吴孟武), Bing-Hui Tian(田冰辉), and Shou-Mei Xiong(熊守美) Chin. Phys. B, 2022, 31 (9):  098105.  DOI: 10.1088/1674-1056/ac7211 Abstract ( 398 )   HTML ( 4 )   PDF (7926KB) ( 175 )   A numerical model is developed by coupling the cellular automaton (CA) method and the lattice Boltzmann method (LBM) to simulate the dendritic growth of Al-Cu alloy in both two and three dimensions. An improved decentered square algorithm is proposed to overcome the artificial anisotropy induced by the CA cells and to realize simulation of dendritic growth with arbitrary orientations. Based on the established CA-LBM model, effects of forced convection and gravity-driven natural convection on dendritic growth are studied. The simulation results show that the blocking effect of dendrites on melt flow is advanced with a larger number of seeds. The competitive growth of the converging columnar dendrites is determined by the interaction between heat flow and forced convection. Gravity-driven natural convection leads to highly asymmetric growth of equiaxed dendrites. With sinking downwards of the heavy solute, chimney-like or mushroom-like solute plumes are formed in the melt in front of the columnar dendrites when they grow along the gravitational direction. More details on dendritic growth of Al-Cu alloy under convection are revealed by 3D simulations.

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Amorphous transformation of ternary Cu45Zr45Ag10 alloy under microgravity condition Ming-Hua Su(苏明华), Fu-Ping Dai(代富平), and Ying Ruan(阮莹) Chin. Phys. B, 2022, 31 (9):  098106.  DOI: 10.1088/1674-1056/ac67c9 Abstract ( 364 )   HTML ( 0 )   PDF (3949KB) ( 119 )   The influences of undercooling rate and cooling rate on the microstructural evolution of ternary Cu45Zr45Ag10 alloy using single-roller melt spinning and drop tube are investigated. The rapidly quenched alloy ribbons achieve a homogeneous glass structure. The microstructure of the droplets transforms from the Cu10Zr7 dendrites plus (Cu10Zr7+AgZr) eutectic into Cu10Zr7 dendrite with the decrease of droplet diameter. As the diameter decreases to 180 μm, the Cu45Zr45Ag10 alloy changes from crystal to amorphous structure, showing that the cooling rate is not the only influence factor and the undercooling play a certain role in the forming of the amorphous alloy at the same time under microgravity condition.

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Designing a P2-type cathode material with Li in both Na and transition metal layers for Na-ion batteries Jianxiang Gao(高健翔), Kai Sun(孙凯), Hao Guo(郭浩), Zhengyao Li(李正耀), Jianlin Wang(王建林), Xiaobai Ma(马小柏), Xuedong Bai(白雪东), and Dongfeng Chen(陈东风) Chin. Phys. B, 2022, 31 (9):  098201.  DOI: 10.1088/1674-1056/ac6b21 Abstract ( 486 )   HTML ( 0 )   PDF (2343KB) ( 151 )   P2-type layered oxides have been considered as promising cathode materials for Na-ion batteries, but the capacity decay resulting from the Na+/vacancy ordering and phase transformation limits their future large-scale applications. Herein, the impact of Li-doping in different layers on the structure and electrochemical performance of P2-type Na0.7Ni0.35Mn0.65O2 is investigated. It can be found that Li ions successfully enter both the Na and transition metal layers. The strategy of Li-doping can improve the cycling stability and rate capability of P2-type layered oxides, which promotes the development of high-performance Na-ion batteries.

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Configurational entropy-induced phase transition in spinel LiMn2O4 Wei Hu(胡伟), Wen-Wei Luo(罗文崴), Mu-Sheng Wu(吴木生), Bo Xu(徐波), and Chu-Ying Ouyang(欧阳楚英) Chin. Phys. B, 2022, 31 (9):  098202.  DOI: 10.1088/1674-1056/ac6863 Abstract ( 427 )   HTML ( 0 )   PDF (1254KB) ( 158 )   The spinel-type LiMn$_{2}$O$_{4}$ is a promising candidate as cathode material for rechargeable Li-ion batteries due to its good thermal stability and safety. Experimentally, it is observed that in this compound there occur the structural phase transitions from cubic ($Fd\bar{3}m)$ to tetragonal ($I4_{1}/{amd}$) phase at slightly below room temperature. To understand the phase transition mechanism, we compare the Gibbs free energy between cubic phase and tetragonal phase by including the configurational entropy. Our results show that the configurational entropy contributes substantially to the stability of the cubic phase at room temperature due to the disordered Mn$^{3+}$/Mn$^{4+}$ distribution as well as the orientation of the Jahn-Teller elongation of the Mn$^{3+}$O$_{6}$ octahedron in the the spinel phase. Meanwhile, the phase transition temperature is predicted to be 267.8 K, which is comparable to the experimentally observed temperature. These results serve as a good complement to the experimental study, and are beneficial to the improving of the electrochemical performance of LiMn$_{2}$O$_{4}$ cathode.

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Liquid-phase synthesis of Li2S and Li3PS4 with lithium-based organic solutions Hot! Jieru Xu(许洁茹), Qiuchen Wang(王秋辰), Wenlin Yan(闫汶琳), Liquan Chen(陈立泉), Hong Li(李泓), and Fan Wu(吴凡) Chin. Phys. B, 2022, 31 (9):  098203.  DOI: 10.1088/1674-1056/ac7459 Abstract ( 538 )   HTML ( 3 )   PDF (7428KB) ( 298 )   Sulfide solid electrolytes are widely regarded as one of the most promising technical routes to realize all-solid-state batteries (ASSBs) due to their high ionic conductivity and favorable deformability. However, the relatively high price of the crucial starting material, Li2S, results in high costs of sulfide solid electrolytes, limiting their practical application in ASSBs. To solve this problem, we develop a new synthesis route of Li2S via liquid-phase synthesis method, employing lithium and biphenyl in 1, 2-dimethoxyethane (DME) ether solvent to form a lithium solution as the lithium precursor. Because of the comparatively strong reducibility of the lithium solution, its reaction with sulfur proceeds effectively even at room temperature. This new synthesis route of Li2S starts with cheap precursors of lithium, sulfur, biphenyl and DME solvent, and the only remaining byproduct (DME solution of biphenyl) after the collection of Li2S product can be recycled and reused. Besides, the reaction can proceed effectively at room temperature with mild condition, reducing energy cost to a great extent. The as-synthesized Li2S owns uniform and extremely small particle size, proved to be feasible in synthesizing sulfide solid electrolytes (such as the solid-state synthesis of Li6PS5Cl). Spontaneously, this lithium solution can be directly employed in the synthesis of Li3PS4 solid electrolytes via liquid-phase synthesis method, in which the centrifugation and heat treatment processes of Li2S are not necessary, providing simplified production process. The as-synthesized Li3PS4 exhibits typical Li+ conductivity of 1.85×10-4 S·cm-1 at 30 ℃.

DATA PAPER

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State-to-state integral cross sections and rate constants for the N+(3P)+HD→NH+/ND++D/H reaction: Accurate quantum dynamics studies Hanghang Chen(陈航航), Zijiang Yang(杨紫江), and Maodu Chen(陈茂笃)† Chin. Phys. B, 2022, 31 (9):  098204.  DOI: 10.1088/1674-1056/ac7e3a Abstract ( 421 )   HTML ( 1 )   PDF (983KB) ( 97 )   The reactive collisions of nitrogen ion with hydrogen and its isotopic variations have great significance in the field of astrophysics. Herein, the state-to-state quantum time-dependent wave packet calculations of N$^{+}$($^{3}$P)$+{\rm HD}\to {\rm NH}^{+}$/ND$^{+} +{\rm D/H}$ reaction are carried out based on the recently developed potential energy surface [Phys. Chem. Chem. Phys. 21 22203 (2019)]. The integral cross sections (ICSs) and rate coefficients of both channels are precisely determined at the state-to-state level. The results of total ICSs and rate coefficients present a dramatic preference on the ND$^{+}$ product over the NH$^{+}$ product, conforming to the long-lived complex-forming mechanism. Product state-resolved ICSs indicate that both the product molecules are difficult to excite to higher vibrational states, and the ND$^{+}$ product has a hotter rotational state distribution. Moreover, the integral cross sections and rate coefficients are precisely determined at the state-to-state level and insights are provided about the differences between the two channels. The present results would provide an important reference for the further experimental studies at the finer level for this interstellar chemical reaction. The datasets presented in this paper, including the ICSs and rate coefficients of the two products for the title reaction, are openly available at https://www.doi.org/10.57760/sciencedb.j00113.00034.

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Sub-stochiometric MoOx by radio-frequency magnetron sputtering as hole-selective passivating contacts for silicon heterojunction solar cells Xiufang Yang(杨秀芳), Shengsheng Zhao(赵生盛), Qian Huang(黄茜), Cao Yu(郁超), Jiakai Zhou(周佳凯), Xiaoning Liu(柳晓宁), Xianglin Su(苏祥林),Ying Zhao(赵颖), and Guofu Hou(侯国付) Chin. Phys. B, 2022, 31 (9):  098401.  DOI: 10.1088/1674-1056/ac5a42 Abstract ( 362 )   HTML ( 0 )   PDF (2176KB) ( 144 )   The silicon heterojunction (SHJ) solar cell has long been considered as one of the most promising candidates for the next-generation PV market. Transition metal oxides (TMOs) show good carrier selectivity when combined with c-Si solar cells. This has led to the rapid demonstration of the remarkable potential of TMOs (especially MoOx) with high work function to replace the p-type a-Si:H emitting layer. MoOx can induce a strong inversion layer on the interface of n-type c-Si, which is beneficial to the extraction and conduction of holes. In this paper, the radio-frequency (RF) magnetron sputtering is used to deposit MoOx films. The optical, electrical and structural properties of MoOx films are measured and analyzed, with focus on the inherent compositions and work function. Then the MoOx films are applied into SHJ solar cells. When the MoOx works as a buffer layer between ITO/p-a-Si:H interface in the reference SHJ solar cell, a conversion efficiency of 19.1% can be obtained. When the MoOx is used as a hole transport layer (HTL), the device indicates a desirable conversion efficiency of 17.5%. To the best of our knowledge, this current efficiency is the highest one for the MoOx film as HTL by RF sputtering.

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Implementation of an 8-bit bit-slice AES S-box with rapid single flux quantum circuits Ruo-Ting Yang(杨若婷), Xin-Yi Xue(薛新伊), Shu-Cheng Yang(杨树澄), Xiao-Ping Gao(高小平), Jie Ren(任洁), Wei Yan(严伟), and Zhen Wang(王镇) Chin. Phys. B, 2022, 31 (9):  098501.  DOI: 10.1088/1674-1056/ac70b9 Abstract ( 431 )   HTML ( 0 )   PDF (5210KB) ( 274 )   Rapid single flux quantum (RSFQ) circuits are a kind of superconducting digital circuits, having properties of a natural gate-level pipelining synchronous sequential circuit, which demonstrates high energy efficiency and high throughput advantage. We find that the high-throughput and high-speed performance of RSFQ circuits can take the advantage of a hardware implementation of the encryption algorithm, whereas these are rarely applied to this field. Among the available encryption algorithms, the advanced encryption standard (AES) algorithm is an advanced encryption standard algorithm. It is currently the most widely used symmetric cryptography algorithm. In this work, we aim to demonstrate the SubByte operation of an AES-128 algorithm using RSFQ circuits based on the SIMIT Nb03 process. We design an AES S-bbox circuit in the RSFQ logic, and compare its operational frequency, power dissipation, and throughput with those of the CMOS-based circuit post-simulated in the same structure. The complete RSFQ S-bbox circuit costs a total of 42237 Josephson junctions with nearly 130 Gbps throughput under the maximum simulated frequency of 16.28 GHz. Our analysis shows that the frequency and throughput of the RSFQ-based S-bbox are about four times higher than those of the CMOS-based S-bbox. Further, we design and fabricate a few typical modules of the S-box. Subsequent measurements demonstrate the correct functioning of the modules in both low and high frequencies up to 28.8 GHz.

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Improvement on short-circuit ability of SiC super-junction MOSFET with partially widened pillar structure Xinxin Zuo(左欣欣), Jiang Lu(陆江), Xiaoli Tian(田晓丽), Yun Bai(白云), Guodong Cheng(成国栋), Hong Chen(陈宏), Yidan Tang(汤益丹), Chengyue Yang(杨成樾), and Xinyu Liu(刘新宇) Chin. Phys. B, 2022, 31 (9):  098502.  DOI: 10.1088/1674-1056/ac6159 Abstract ( 420 )   HTML ( 0 )   PDF (1544KB) ( 239 )   A novel 1200 V SiC super-junction (SJ) MOSFET with a partially widened pillar structure is proposed and investigated by using the two-dimensional numerical simulation tool. Based on the SiC SJ MOSFET structure, a partially widened P-region is added at the SJ pillar region to improve the short-circuit (SC) ability. After investigating the position and doping concentration of the widened P-region, an optimal structure is determined. From the simulation results, the SC withstand times (SCWTs) of the conventional trench MOSFET (CT-MOSFET), the SJ MOSFET, and the proposed structure at 800 V DC bus voltage are 15 μs, 17 μs, and 24 μs, respectively. The SCWTs of the proposed structure are increased by 60% and 41.2% in comparison with that of the other two structures. The main reason for the proposed structure with an enhanced SC capability is related to the effective suppression of saturation current at the high DC bias conditions by using a modulated P-pillar region. Meanwhile, a good Baliga's FOM ($BV^{2}/R_{\rm on}$) also can be achieved in the proposed structure due to the advantage of the SJ structure. In addition, the fabrication technology of the proposed structure is compatible with the standard epitaxy growth method used in the SJ MOSFET. As a result, the SJ structure with this feasible optimization skill presents an effect on improving the SC reliability of the SiC SJ MOSFET without the degeneration of the Baliga's FOM.

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Phosphorus diffusion and activation in fluorine co-implanted germanium after excimer laser annealing Chen Wang(王尘), Wei-Hang Fan(范伟航), Yi-Hong Xu(许怡红), Yu-Chao Zhang(张宇超), Hui-Chen Fan(范慧晨), Cheng Li(李成), and Song-Yan Cheng(陈松岩) Chin. Phys. B, 2022, 31 (9):  098503.  DOI: 10.1088/1674-1056/ac6db3 Abstract ( 410 )   HTML ( 0 )   PDF (1120KB) ( 247 )   The diffusion and the activation of phosphorus in phosphorus and fluorine co-implanted Ge after being annealed by excimer laser are investigated. The results prove that the fluorine element plays an important role in suppressing phosphorus diffusion and enhancing phosphorus activation. Moreover, the rapid thermal annealing process is utilized to evaluate and verify the role of fluorine element. During the initial annealing of co-implanted Ge, it is easier to form high bonding energy FnVm clusters which can stabilize the excess vacancies, resulting in the reduced vacancy-assisted diffusion of phosphorus. The maximum activation concentration of about 4.4×1020 cm-3 with a reduced diffusion length and dopant loss is achieved in co-implanted Ge that is annealed at a tailored laser fluence of 175 mJ/cm2. The combination of excimer laser annealing and co-implantation technique provides a reference and guideline for high level n-type doping in Ge and is beneficial to its applications in the scaled Ge MOSFET technology and other devices.

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Growth of high material quality InAs/GaSb type-II superlattice for long-wavelength infrared range by molecular beam epitaxy Fang-Qi Lin(林芳祁), Nong Li(李农), Wen-Guang Zhou(周文广), Jun-Kai Jiang(蒋俊锴), Fa-Ran Chang(常发冉), Yong Li(李勇), Su-Ning Cui(崔素宁), Wei-Qiang Chen(陈伟强), Dong-Wei Jiang(蒋洞微), Hong-Yue Hao(郝宏玥), Guo-Wei Wang(王国伟), Ying-Qiang Xu(徐应强), and Zhi-Chuan Niu(牛智川) Chin. Phys. B, 2022, 31 (9):  098504.  DOI: 10.1088/1674-1056/ac615d Abstract ( 447 )   HTML ( 1 )   PDF (1453KB) ( 196 )   By optimizing the V/III beam-equivalent pressure ratio, a high-quality InAs/GaSb type-II superlattice material for the long-wavelength infrared (LWIR) range is achieved by molecular beam epitaxy (MBE). High-resolution x-ray diffraction (HRXRD), atomic force microscopy (AFM), and Fourier transform infrared (FTIR) spectrometer are used to characterize the material growth quality. The results show that the full width at half maximum (FWHM) of the superlattice zero-order diffraction peak, the mismatching of the superlattice zero-order diffraction peak between the substrate diffraction peaks, and the surface roughness get the best results when the beam-equivalent pressure (BEP) ratio reaches the optimal value, which are 28 arcsec, 13 arcsec, and 1.63 Å, respectively. The intensity of the zero-order diffraction peak is strongest at the optimal value. The relative spectral response of the LWIR detector shows that it exhibits a 100% cut-off wavelength of 12.6 μm at 77 K. High-quality epitaxial materials have laid a good foundation for preparing high-performance LWIR detector.

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Temporal response of laminated graded-bandgap GaAs-based photocathode with distributed Bragg reflection structure: Model and simulation Zi-Heng Wang(王自衡), Yi-Jun Zhang(张益军), Shi-Man Li(李诗曼), Shan Li(李姗), Jing-Jing Zhan(詹晶晶), Yun-Sheng Qian(钱芸生), Feng Shi(石峰), Hong-Chang Cheng(程宏昌), Gang-Cheng Jiao(焦岗成), and Yu-Gang Zeng(曾玉刚) Chin. Phys. B, 2022, 31 (9):  098505.  DOI: 10.1088/1674-1056/ac6334 Abstract ( 348 )   HTML ( 0 )   PDF (1308KB) ( 111 )   To describe the dynamic response characteristics of the laminated graded-bandgap GaAs-based photocathode with distributed Bragg reflection structure, a general theoretical temporal response model is deduced by combining the unsteady continuity equation and numerical calculation method. Through the model, the contribution of the distribution Bragg reflection structure and graded-bandgap emission layer to the temporal response are investigated. Meanwhile, the relationships between the temporal response characteristics of the laminated GaAs-based photocathode and different structural parameters are also analyzed, including average electron decay time, emission layer thickness, and incident light wavelength. It is found that the introduction of distribution Bragg reflection (DBR) layer solves the discrepancy between the absorption capability of the emission layer and the temporal response. Moreover, the distributed Bragg reflection layer can improve the time response by optimizing the initial photoelectron distribution. The improvement effect of the DBR layer on the temporal response is enhanced with the emission layer thickness decreasing or the incident light wavelength increasing. These results explain the effect of the DBR layer of the photocathode on the dynamic characteristics, which can offer a new insight into the dynamic research of GaAs-based photocathode.

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Bioinspired tactile perception platform with information encryption function Hot! Zhi-Wen Shi(石智文), Zheng-Yu Ren(任征宇), Wei-Sheng Wang(王伟胜), Hui Xiao(肖惠), Yu-Heng Zeng(曾俞衡), and Li-Qiang Zhu(竺立强) Chin. Phys. B, 2022, 31 (9):  098506.  DOI: 10.1088/1674-1056/ac7a15 Abstract ( 636 )   HTML ( 6 )   PDF (3270KB) ( 289 )   Mimicking tactile perception is critical to the development of advanced interactive neuromorphic platforms. Inspired by cutaneous perceptual functions, a bionic tactile perceptual platform is proposed. PDMS-based tactile sensors act as bionic skin touch receptors. Flexible indium tin oxide neuromorphic transistors fabricated with a single-step mask processing act as artificial synapses. Thus, the tactile perceptual platform possesses the ability of information processing. Interestingly, the flexible tactile perception platform can find applications in information encryption and decryption. With adoption of cipher, signal transmitted by the perception platform is encrypted. Thus, the security of information transmission is effectively improved. The flexible tactile perceptual platform would have potentials in cognitive wearable devices, advanced human-machine interaction system, and intelligent bionic robots.

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Quantum oscillations in a hexagonal boron nitride-supported single crystalline InSb nanosheet Li Zhang(张力), Dong Pan(潘东), Yuanjie Chen(陈元杰), Jianhua Zhao(赵建华), and Hongqi Xu(徐洪起) Chin. Phys. B, 2022, 31 (9):  098507.  DOI: 10.1088/1674-1056/ac7455 Abstract ( 362 )   HTML ( 0 )   PDF (8437KB) ( 124 )   A gated Hall-bar device is made from an epitaxially grown, free-standing InSb nanosheet on a hexagonal boron nitride (hBN) dielectric/graphite gate structure and the electron transport properties in the InSb nanosheet are studied by gate-transfer characteristic and magnetotransport measurements at low temperatures. The measurements show that the carriers in the InSb nanosheet are of electrons and the carrier density in the nanosheet can be highly efficiently tuned by the graphite gate. The mobility of the electrons in the InSb nanosheet is extracted from low-field magneotransport measurements and a value of the mobility exceeding $\sim 1.8\times10^4$ cm$^{2}\cdot$V$^{-1}\cdot$s$^{-1}$ is found. High-field magentotransport measurements show well-defined Shubnikov-de Haas (SdH) oscillations in the longitudinal resistance of the InSb nanosheet. Temperature-dependent measurements of the SdH oscillations are carried out and key transport parameters, including the electron effective mass $m^{\ast }\sim 0.028 m_{0}$ and the quantum lifetime $\tau \sim 0.046 $ ps, in the InSb nanosheet are extracted. It is for the first time that such experimental measurements have been reported for a free-standing InSb nanosheet and the results obtained indicate that InSb nanosheet/hBN/graphite gate structures can be used to develop advanced quantum devices for novel physics studies and for quantum technology applications.

INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY

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Regulation of the intermittent release of giant unilamellar vesicles under osmotic pressure Qi Zhou(周琪), Ping Wang(王平), Bei-Bei Ma(马贝贝), Zhong-Ying Jiang(蒋中英), and Tao Zhu(朱涛) Chin. Phys. B, 2022, 31 (9):  098701.  DOI: 10.1088/1674-1056/ac4a69 Abstract ( 380 )   HTML ( 2 )   PDF (1715KB) ( 101 )   Osmotic pressure can break the fluid balance between intracellular and extracellular solutions. In hypo-osmotic solution, water molecules, which transfer into the cell and burst, are driven by the concentration difference of solute across the semi-permeable membrane. The complicated dynamic processes of intermittent bursts have been previously observed. However, the underlying physical mechanism has yet to be thoroughly explored and analyzed. Here, the intermittent release of inclusion in giant unilamellar vesicles was investigated quantitatively, applying the combination of experimental and theoretical methods in the hypo-osmotic medium. Experimentally, we adopted a highly sensitive electron multiplying charge-coupled device to acquire intermittent dynamic images. Notably, the component of the vesicle phospholipids affected the stretch velocity, and the prepared solution of vesicles adjusted the release time. Theoretically, we chose equations and numerical simulations to quantify the dynamic process in phases and explored the influences of physical parameters such as bilayer permeability and solution viscosity on the process. It was concluded that the time taken to achieve the balance of giant unilamellar vesicles was highly dependent on the molecular structure of the lipid. The pore lifetime was strongly related to the internal solution environment of giant unilamellar vesicles. The vesicles prepared in viscous solution were able to visualize long-lived pores. Furthermore, the line tension was measured quantitatively by the release velocity of inclusion, which was of the same order of magnitude as the theoretical simulation. In all, the experimental values well matched the theoretical values. Our investigation clarified the physical regulatory mechanism of intermittent pore formation and inclusion release, which provides an important reference for the development of novel technologies such as gene therapy based on transmembrane transport as well as controlled drug delivery based on liposomes.

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X-ray phase-sensitive microscope imaging with a grating interferometer: Theory and simulation Jiecheng Yang(杨杰成), Peiping Zhu(朱佩平), Dong Liang(梁栋), Hairong Zheng(郑海荣), and Yongshuai Ge(葛永帅) Chin. Phys. B, 2022, 31 (9):  098702.  DOI: 10.1088/1674-1056/ac600e Abstract ( 490 )   HTML ( 0 )   PDF (1105KB) ( 90 )   A general theoretical framework is presented to explain the formation of the phase signal in an x-ray microscope integrated with a grating interferometer, which simultaneously enables the high spatial resolution imaging and the improved image contrast. By using this theory, several key parameters of phase contrast imaging can be predicted, for instance, the fringe visibility and period, and the conversion condition from the differential phase imaging (DPI) to the phase difference imaging (PDI). Additionally, numerical simulations are performed with certain x-ray optical components and imaging geometry. Comparison with the available experimental measurement [Appl. Phys. Lett. 113 063105 (2018)] demonstrates the accuracy of this developed quantitative analysis method of x-ray phase-sensitive microscope imaging.

TOPICAL REVIEW—Celebrating 30 Years of Chinese Physics B

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Anionic redox reaction mechanism in Na-ion batteries Xueyan Hou(侯雪妍), Xiaohui Rong(容晓晖), Yaxiang Lu(陆雅翔), and Yong-Sheng Hu(胡勇胜) Chin. Phys. B, 2022, 31 (9):  098801.  DOI: 10.1088/1674-1056/ac81ab Abstract ( 442 )   HTML ( 2 )   PDF (2096KB) ( 219 )   Na-ion batteries (NIBs), as one of the next-generation rechargeable battery systems, hold great potential in large-scale energy storage applications owing to the abundance and costeffectiveness of sodium resources. Despite the extensive exploration of electrode materials, the relatively low attainable capacity of NIBs hinders their practical application. In recent years, the anionic redox reaction (ARR) in NIBs has been emerging as a new paradigm to deliver extra capacity and thus offers an opportunity to break through the intrinsic energy density limit. In this review, the fundamental investigation of the ARR mechanism and the latest exploration of cathode materials are summarized, in order to highlight the significance of reversible anionic redox and suggest prospective developing directions.

ERRATUM

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Erratum to “Accurate determination of film thickness by low-angle x-ray reflection” Ming Xu(徐明), Tao Yang(杨涛), Wenxue Yu(于文学), Ning Yang(杨宁), Cuixiu Liu(刘翠秀), Zhenhong Mai(麦振洪), Wuyan Lai(赖武彦), and Kun Tao(陶琨) Chin. Phys. B, 2022, 31 (9):  099901.  DOI: 10.1088/1674-1056/ac89d3 Abstract ( 376 )   HTML ( 1 )   PDF (769KB) ( 55 )   Equation (6) in Chin. Phys. 09 0833 (2000) is corrected. All subsequent derivations were given based on the correct Eq. (6), so the conclusions in the paper are not affected by the errata.