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14 November 2023, Volume 32 Issue 12 Previous issue    Next issue

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TOPICAL REVIEW—Physics in micro-LED and quantum dots devices

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Materials and device engineering to achieve high-performance quantum dots light emitting diodes for display applications Changfeng Han(韩长峰), Ruoxi Qian(钱若曦), Chaoyu Xiang(向超宇), and Lei Qian(钱磊) Chin. Phys. B, 2023, 32 (12):  128506.  DOI: 10.1088/1674-1056/acb916 Abstract ( 126 )   HTML ( 1 )   PDF (1045KB) ( 78 )   Quantum dots (QDs) have attracted wide attention from academia and industry because of their advantages such as high emitting efficiency, narrow half-peak width, and continuously adjustable emitting wavelength. QDs light emitting diodes (QLEDs) are expected to become the next generation commercial display technology. This paper reviews the progress of QLED from physical mechanism, materials, to device engineering. The strategies to improve QLED performance from the perspectives of quantum dot materials and device structures are summarized.

TOPICAL REVIEW—Post-Moore era: Materials and device physics

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Ferroelectric domain wall memory Yiming Li(李一鸣), Jie Sun(孙杰), and Anquan Jiang(江安全) Chin. Phys. B, 2023, 32 (12):  128504.  DOI: 10.1088/1674-1056/ace4b6 Abstract ( 102 )   HTML ( 0 )   PDF (1883KB) ( 47 )   Ferroelectric domain walls appear as sub-nanometer-thick topological interfaces separating two adjacent domains in different orientations, and can be repetitively created, erased, and moved during programming into different logic states for the nonvolatile memory under an applied electric field, providing a new paradigm for highly miniaturized low-energy electronic devices. Under some specific conditions, the charged domain walls are conducting, differing from their insulating bulk domains. In the past decade, the emergence of atomic-layer scaling solid-state electronic devices is such demonstration, resulting in the rapid rise of domain wall nano-electronics. This review aims to the latest development of ferroelectric domain-wall memories with the presence of the challenges and opportunities and the roadmap to their future commercialization.

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Recent progress on ambipolar 2D semiconductors in emergent reconfigurable electronics and optoelectronics Yuehao Zhao(赵月豪), Haoran Sun(孙浩然), Zhe Sheng(盛喆), David Wei Zhang(张卫),Peng Zhou(周鹏), and Zengxing Zhang(张增星) Chin. Phys. B, 2023, 32 (12):  128505.  DOI: 10.1088/1674-1056/ad08a5 Abstract ( 91 )   HTML ( 0 )   PDF (2070KB) ( 77 )   In these days, the increasing massive data are being produced and demanded to be processed with the rapid growth of information technology. It is difficult to rely solely on the shrinking of semiconductor devices and scale-up of the integrated circuits (ICs) again in the foreseeable future. Exploring new materials, new-principle semiconductor devices and new computing architectures is becoming an urgent topic in this field. Ambipolar two-dimensional (2D) semiconductors, possessing excellent electrostatic field controllability and flexibly modulated major charge carriers, offer a possibility to construct reconfigurable devices and enable the ICs with new functions, showing great potential in computing capacity, energy efficiency, time delay and cost. This review focuses on the recent significant advancements in reconfigurable electronic and optoelectronic devices of ambipolar 2D semiconductors, and demonstrates their potential approach towards ICs, like reconfigurable circuits and neuromorphic chips. It is expected to help readers understand the device design principle of ambipolar 2D semiconductors, and push forward exploring more new-principle devices and new-architecture computing circuits, and even their product applications.

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Recent progress on two-dimensional ferroelectrics: Material systems and device applications Zhiwei Fan(范芷薇), Jingyuan Qu(渠靖媛), Tao Wang(王涛), Yan Wen(温滟), Ziwen An(安子文), Qitao Jiang(姜琦涛), Wuhong Xue(薛武红), Peng Zhou(周鹏), and Xiaohong Xu(许小红) Chin. Phys. B, 2023, 32 (12):  128508.  DOI: 10.1088/1674-1056/ad08a4 Abstract ( 137 )   HTML ( 1 )   PDF (8731KB) ( 74 )   Ferroelectrics are a type of material with a polar structure and their polarization direction can be inverted reversibly by applying an electric field. They have attracted tremendous attention for their extensive applications in non-volatile memory, sensors and neuromorphic computing. However, conventional ferroelectric materials face insulating and interfacial issues in the commercialization process. In contrast, two-dimensional (2D) ferroelectric materials usually have excellent semiconductor performance, clean van der Waals interfaces and robust ferroelectric order in atom-thick layers, and hold greater promise for constructing multifunctional ferroelectric optoelectronic devices and nondestructive ultra-high-density memory. Recently, 2D ferroelectrics have obtained impressive breakthroughs, showing overwhelming superiority. Herein, firstly, the progress of experimental research on 2D ferroelectric materials is reviewed. Then, the preparation of 2D ferroelectric devices and their applications are discussed. Finally, the future development trend of 2D ferroelectrics is looked at.

SPECIAL TOPIC—Post-Moore era: Materials and device physics

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P-type cold-source field-effect transistors with TcX2 and ReX2 (X=S, Se) cold source electrodes: A computational study Qianwen Wang(汪倩文), Jixuan Wu(武继璇), Xuepeng Zhan(詹学鹏),Pengpeng Sang(桑鹏鹏), and Jiezhi Chen(陈杰智) Chin. Phys. B, 2023, 32 (12):  127203.  DOI: 10.1088/1674-1056/ad0116 Abstract ( 102 )   HTML ( 1 )   PDF (969KB) ( 123 )   Cold-source field-effect transistors (CS-FETs) have been developed to overcome the major challenge of power dissipation in modern integrated circuits. Cold metals suitable for n-type CS-FETs have been proposed as the ideal electrode to filter the high-energy electrons and break the thermal limit on subthreshold swing (SS). In this work, regarding the p-type CS-FETs, we propose TcX2 and ReX2 (X = S, Se) as the injection source to realize the sub-thermal switching for holes. First-principles calculations unveils the cold-metal characteristics of monolayer TcX2 and ReX2, possessing a sub-gap below the Fermi level and a decreasing DOS with energy. Quantum device simulations demonstrate that TcX2 and ReX2 can enable the cold source effects in WSe2 p-type FETs, achieving steep SS of 29-38 mV/dec and high on/off ratios of (2.3-5.6)×107. Moreover, multilayer ReS2 retains the cold metal characteristic, thus ensuring similar CS-FET performances to that of the monolayer source. This work underlines the significance of cold metals for the design of p-type CS-FETs.

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Tensile stress regulated microstructures and ferroelectric properties of Hf0.5Zr0.5O2 films Siying Huo(霍思颖), Junfeng Zheng(郑俊锋), Yuanyang Liu(刘远洋), Yushan Li(李育姗),Ruiqiang Tao(陶瑞强), Xubing Lu(陆旭兵), and Junming Liu(刘俊明) Chin. Phys. B, 2023, 32 (12):  127701.  DOI: 10.1088/1674-1056/acfb79 Abstract ( 90 )   HTML ( 0 )   PDF (1242KB) ( 61 )   The discovery of ferroelectricity in HfO2 based materials reactivated the research on ferroelectric memory. However, the complete mechanism underlying its ferroelectricity remains to be fully elucidated. In this study, we conducted a systematic study on the microstructures and ferroelectric properties of Hf0.5Zr0.5O2 (HZO) thin films with various annealing rates in the rapid thermal annealing. It was observed that the HZO thin films with higher annealing rates demonstrate smaller grain size, reduced surface roughness and a higher portion of orthorhombic phase. Moreover, these films exhibited enhanced polarization values and better fatigue cycles compared to those treated with lower annealing rates. The grazing incidence x-ray diffraction measurements revealed the existence of tension stress in the HZO thin films, which was weakened with decreasing annealing rate. Our findings revealed that this internal stress, along with the stress originating from the top/bottom electrode, plays a crucial role in modulating the microstructure and ferroelectric properties of the HZO thin films. By carefully controlling the annealing rate, we could effectively regulate the tension stress within HZO thin films, thus achieving precise control over their ferroelectric properties. This work established a valuable pathway for tailoring the performance of HZO thin films for various applications.

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Reconfigurable Mott electronics for homogeneous neuromorphic platform Zhen Yang(杨振), Ying-Ming Lu(路英明), and Yu-Chao Yang(杨玉超) Chin. Phys. B, 2023, 32 (12):  128401.  DOI: 10.1088/1674-1056/ad02e8 Abstract ( 81 )   HTML ( 0 )   PDF (4581KB) ( 50 )   To simplify the fabrication process and increase the versatility of neuromorphic systems, the reconfiguration concept has attracted much attention. Here, we developed a novel electrochemical VO2 (EC-VO2) device, which can be reconfigured as synapses or LIF neurons. The ionic dynamic doping contributed to the resistance changes of VO2, which enables the reversible modulation of device states. The analog resistance switching and tunable LIF functions were both measured based on the same device to demonstrate the capacity of reconfiguration. Based on the reconfigurable EC-VO2, the simulated spiking neural network model exhibited excellent performances by using low-precision weights and tunable output neurons, whose final accuracy reached 91.92%.

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β-Ga2O3 junction barrier Schottky diode with NiO p-well floating field rings Qiming He(何启鸣), Weibing Hao(郝伟兵), Qiuyan Li(李秋艳), Zhao Han(韩照), Song He(贺松),Qi Liu(刘琦), Xuanze Zhou(周选择), Guangwei Xu(徐光伟), and Shibing Long(龙世兵) Chin. Phys. B, 2023, 32 (12):  128507.  DOI: 10.1088/1674-1056/accf69 Abstract ( 95 )   HTML ( 0 )   PDF (2945KB) ( 54 )   Recently, β-Ga2O3, an ultra-wide bandgap semiconductor, has shown great potential to be used in power devices blessed with its unique material properties. For instance, the measured average critical field of the vertical Schottky barrier diode (SBD) based on β-Ga2O3 has reached 5.45 MV/cm, and no device in any material has measured a greater before. However, the high electric field of the β-Ga2O3 SBD makes it challenging to manage the electric field distribution and leakage current. Here, we show β-Ga2O3 junction barrier Schottky diode with NiO p-well floating field rings (FFRs). For the central anode, we filled a circular trench array with NiO to reduce the surface field under the Schottky contact between them to reduce the leakage current of the device. For the anode edge, experimental results have demonstrated that the produced NiO/β-Ga2O3 heterojunction FFRs enable the spreading of the depletion region, thereby mitigating the crowding effect of electric fields at the anode edge. Additionally, simulation results indicated that the p-NiO field plate structure designed at the edges of the rings and central anode can further reduce the electric field. This work verified the feasibility of the heterojunction FFRs in β-Ga2O3 devices based on the experimental findings and provided ideas for managing the electric field of β-Ga2O3 SBD.

SPECIAL TOPIC—Optical field manipulation

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Tailoring OAM spectrum of high-order harmonic generation driven by two mixed Laguerre-Gaussian beams with nonzero radial nodes Beiyu Wang(汪倍羽), Jiaxin Han(韩嘉鑫), and Cheng Jin(金成) Chin. Phys. B, 2023, 32 (12):  124208.  DOI: 10.1088/1674-1056/ad0144 Abstract ( 114 )   HTML ( 0 )   PDF (4126KB) ( 57 )   The extreme ultraviolet (XUV) light beam carrying orbital angular momentum (OAM) can be produced via high-order harmonic generation (HHG) due to the interaction of an intense vortex infrared laser and a gas medium. Here we show that the OAM spectrum of vortex HHG can be readily tailored by varying the radial node (from 0 to 2) in the driving laser consisting of two mixed Laguerre-Gaussian (LG) beams. We find that due to the change in spatial profile of HHG, the distribution range of the OAM spectrum can be broadened and its shape can be modified by increasing the radial node. We also show that the OAM mode range becomes much wider and its distribution shape becomes more symmetric when the harmonic order is increased from the plateau to the cutoff when the driving laser has the nonzero radial nodes. Through the map of coherence length and the evolution of harmonic field in the medium, we reveal that the favorable off-axis phase-matching conditions are greatly modified due to the change of intensity and phase distributions of driving laser with the radial node. We anticipate this work to stimulate some interests in generating the XUV vortex beam with tunable OAM spectrum through the gaseous HHG process achieved by manipulating the mode properties of the driving laser beam.

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Multi-channel generation of vortex beams with controllable polarization states and orbital angular momentum Ziyao Lyu(吕子瑶), Pan Wang(王潘), and Changshun Wang(王长顺) Chin. Phys. B, 2023, 32 (12):  124209.  DOI: 10.1088/1674-1056/ace767 Abstract ( 99 )   HTML ( 0 )   PDF (1217KB) ( 57 )   Optical vortices with tunable polarization states and topological charges are widely investigated in various physical systems and practical devices for high-capacity optical communication. However, this kind of structured light beams is usually generated using several polarization and spatial phase devices, which decreases the configurability of optical systems. Here, we have designed a kind of polarized optical multi-vortices generator based on the Stokes-Mueller formalism and cross-phase modulation. In our scheme, multi-channel generation of polarized vortex beams can be realized through a single optical element and a single-input Gaussian beam. The polarization states and orbital angular momentum of the generated light beams are all-optically controllable. Furthermore, the proposed polarized optical multi-vortices generator has also been demonstrated experimentally through one-step holographic recording in an azobenzene liquid-crystalline film and the experimental results agree with theoretical analysis.

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Calibration of quantitative rescattering model for simulating vortex high-order harmonic generation driven by Laguerre-Gaussian beam with nonzero orbital angular momentum Jiaxin Han(韩嘉鑫), Zhong Guan(管仲), Beiyu Wang(汪倍羽), and Cheng Jin(金成) Chin. Phys. B, 2023, 32 (12):  124210.  DOI: 10.1088/1674-1056/acfa86 Abstract ( 92 )   HTML ( 0 )   PDF (3394KB) ( 40 )   We calibrate the macroscopic vortex high-order harmonic generation (HHG) obtained by the quantitative rescattering (QRS) model to compute single-atom induced dipoles against that by solving the time-dependent Schrödinger equation (TDSE). We show that the QRS perfectly agrees with the TDSE under the favorable phase-matching condition, and the QRS can accurately predict the main features in the spatial profiles of vortex HHG if the phase-matching condition is not good. We uncover that harmonic emissions from short and long trajectories are adjusted by the phase-matching condition through the time-frequency analysis and the QRS can simulate the vortex HHG accurately only when the interference between two trajectories is absent. This work confirms that it is an efficient way to employ the QRS model in the single-atom response for precisely simulating the macroscopic vortex HHG.

REVIEW

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Applications and potentials of machine learning in optoelectronic materials research: An overview and perspectives Cheng-Zhou Zhang(张城洲) and Xiao-Qian Fu(付小倩) Chin. Phys. B, 2023, 32 (12):  126103.  DOI: 10.1088/1674-1056/ad01a4 Abstract ( 107 )   HTML ( 0 )   PDF (3403KB) ( 63 )   Optoelectronic materials are essential for today's scientific and technological development, and machine learning provides new ideas and tools for their research. In this paper, we first summarize the development history of optoelectronic materials and how materials informatics drives the innovation and progress of optoelectronic materials and devices. Then, we introduce the development of machine learning and its general process in optoelectronic materials and describe the specific implementation methods. We focus on the cases of machine learning in several application scenarios of optoelectronic materials and devices, including the methods related to crystal structure, properties (defects, electronic structure) research, materials and devices optimization, material characterization, and process optimization. In summarizing the algorithms and feature representations used in different studies, it is noted that prior knowledge can improve optoelectronic materials design, research, and decision-making processes. Finally, the prospect of machine learning applications in optoelectronic materials is discussed, along with current challenges and future directions. This paper comprehensively describes the application value of machine learning in optoelectronic materials research and aims to provide reference and guidance for the continuous development of this field.

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Research progress in quantum key distribution Chun-Xue Zhang(张春雪), Dan Wu(吴丹), Peng-Wei Cui(崔鹏伟), Jun-Chi Ma(马俊驰),Yue Wang(王玥), and Jun-Ming An(安俊明) Chin. Phys. B, 2023, 32 (12):  124207.  DOI: 10.1088/1674-1056/acfd16 Abstract ( 112 )   HTML ( 1 )   PDF (601KB) ( 155 )   Quantum key distribution (QKD) is a sophisticated method for securing information by leveraging the principles of quantum mechanics. Its objective is to establish a confidential key between authorized partners who are connected via both a quantum channel and a classical authentication channel. This paper presents a comprehensive overview of QKD protocols, chip-based QKD systems, quantum light sources, quantum detectors, fiber-based QKD networks, space-based QKD systems, as well as the applications and prospects of QKD technology.

RAPID COMMUNICATION

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Complete population transfer between next-adjacent energy levels of a transmon qudit Hot! Yingshan Zhang(张颖珊), Pei Liu(刘培), Jingning Zhang(张静宁), Ruixia Wang(王睿侠), Weiyang Liu(刘伟洋), Jiaxiu Han(韩佳秀), Yirong Jin(金贻荣), and Haifeng Yu(于海峰) Chin. Phys. B, 2023, 32 (12):  120306.  DOI: 10.1088/1674-1056/ad02e4 Abstract ( 200 )   HTML ( 0 )   PDF (15380KB) ( 246 )   The utilization of qudits in quantum systems has led to significant advantages in quantum computation and information processing. Therefore, qudits have gained increased attention in recent research for their precise and efficient operations. In this work, we demonstrate the complete population transfer between the next-adjacent energy levels of a transmon qudit using the Pythagorean coupling method and energy level mapping. We achieve a |0> to |2> transfer with a process fidelity of 97.76% in the subspace spanned by |0> to |2>. Moreover, the transfer operation is achieved within a remarkably fast timescale, as short as 20 ns. This study may present a promising avenue for enhancing the operation flexibility and efficiency of qudits in future implementations.

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Chair-like N66- in AlN3 with high-energy density Hot! Shi-Tai Guo(郭世泰), Zhen-Zhen Xu(徐真真), Yan-Lei Geng(耿延雷), Qi Rui(芮琦), Dian-Chen Du(杜殿臣), Jian-Fu Li(李建福), and Xiao-Li Wang(王晓丽) Chin. Phys. B, 2023, 32 (12):  126202.  DOI: 10.1088/1674-1056/acfd1a Abstract ( 233 )   HTML ( 0 )   PDF (1815KB) ( 202 )   The search for stable novel polynitrogen clusters has garnered significant attention in the field of energetic materials due to their potential applications as high-energy-density materials. In this study, a chair-like N66- ring with N-N single bonds in the AlN3 compound is theoretically predicted through first-principles calculations in conjunction with an unbiased structure searching method. The predicted AlN3 phase exhibits high kinetic and thermodynamic stability, along with a high energy density of 5.04 kJ/g relative to AlN and N2 gas. Additionally, its detonation velocity and pressure are estimated to reach 12.93 km/s and 1009.63 kbar, respectively. These values are greater than those of TNT and HMX, positioning it as a promising candidate for high-energy-density materials in the field of explosive combustion. The analysis of electronic properties and the related chemical bonding patterns indicates that the compounds are stabilized by both Coulomb interactions and covalent bonds. More importantly, the calculated formation of enthalpy indicates that the N66- anions within AlN3 can be synthesized by compressing AlN and N2 at a moderate pressure (46 GPa). These findings present a viable approach for synthesizing and stabilizing the all-nitrogen N66- anions.

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Ultralow-temperature heat transport study of noncentrosymmetric superconductor CaPtAs Hot! Yimin Wan(万一民), Erjian Cheng(程二建), Yuxin Chen(陈宇鑫), Chengcheng Zhao(赵成成), Chengpeng Tu(涂成鹏), Dongzhe Dai(戴东喆), Xiaofan Yang(杨小帆), Lu Xin(辛路), Wu Xie(谢武), Huiqiu Yuan(袁辉球), and Shiyan Li(李世燕) Chin. Phys. B, 2023, 32 (12):  127403.  DOI: 10.1088/1674-1056/ad02e9 Abstract ( 184 )   HTML ( 0 )   PDF (1028KB) ( 137 )   The noncentrosymmetric superconductor CaPtAs with time-reversal symmetry breaking in its superconducting state was previously proposed to host nodal superconductivity. Here, by employing ultralow-temperature thermal conductivity measurement on CaPtAs single crystal, we study its superconducting gap structure. A negligible residual linear term of thermal conductivity (κ0/T) in zero magnetic field and the field dependence of κ0/T indicate that CaPtAs has multiple superconducting gaps with a dominant s-wave component. This is consistent with recent nuclear quadrupole resonance measurements on CaPtAs. Our work puts a strong constraint on the theories to describe the superconducting pairing symmetry of CaPtAs.

GENERAL

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From breather solutions to lump solutions: A construction method for the Zakharov equation Feng Yuan(袁丰), Behzad Ghanbari, Yongshuai Zhang(张永帅), and Abdul Majid Wazwaz Chin. Phys. B, 2023, 32 (12):  120201.  DOI: 10.1088/1674-1056/acf706 Abstract ( 99 )   HTML ( 0 )   PDF (4216KB) ( 44 )   Periodic solutions of the Zakharov equation are investigated. By performing the limit operation λ2l-1 to λ1 on the eigenvalues of the Lax pair obtained from the n-fold Darboux transformation, an order-n breather-positon solution is first obtained from a plane wave seed. It is then proven that an order-n lump solution can be further constructed by taking the limit λ1 to λ0 on the breather-positon solution, because the unique eigenvalue λ0 associated with the Lax pair eigenfunction Ψ(λ0)=0 corresponds to the limit of the infinite-periodic solutions. A convenient procedure of generating higher-order lump solutions of the Zakharov equation is also investigated based on the idea of the degeneration of double eigenvalues in multi-breather solutions.

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Nondegenerate solitons of the (2+1)-dimensional coupled nonlinear Schrödinger equations with variable coefficients in nonlinear optical fibers Wei Yang(杨薇), Xueping Cheng(程雪苹), Guiming Jin(金桂鸣), and Jianan Wang(王佳楠) Chin. Phys. B, 2023, 32 (12):  120202.  DOI: 10.1088/1674-1056/acf282 Abstract ( 87 )   HTML ( 0 )   PDF (6669KB) ( 30 )   We derive the multi-hump nondegenerate solitons for the (2+1)-dimensional coupled nonlinear Schrödinger equations with propagation distance dependent diffraction, nonlinearity and gain (loss) using the developing Hirota bilinear method, and analyze the dynamical behaviors of these nondegenerate solitons. The results show that the shapes of the nondegenerate solitons are controllable by selecting different wave numbers, varying diffraction and nonlinearity parameters. In addition, when all the variable coefficients are chosen to be constant, the solutions obtained in this study reduce to the shape-preserving nondegenerate solitons. Finally, it is found that the nondegenerate two-soliton solutions can be bounded to form a double-hump two-soliton molecule after making the velocity of one double-hump soliton resonate with that of the other one.

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Diverse soliton solutions and dynamical analysis of the discrete coupled mKdV equation with 4×4 Lax pair Xue-Ke Liu(刘雪珂) and Xiao-Yong Wen(闻小永) Chin. Phys. B, 2023, 32 (12):  120203.  DOI: 10.1088/1674-1056/acf122 Abstract ( 127 )   HTML ( 0 )   PDF (3150KB) ( 129 )   Under consideration in this study is the discrete coupled modified Korteweg-de Vries (mKdV) equation with 4×4 Lax pair. Firstly, through using continuous limit technique, this discrete equation can be mapped to the coupled KdV and mKdV equations, which may depict the development of shallow water waves, the optical soliton propagation in cubic nonlinear media and the Alfven wave in a cold collision-free plasma. Secondly, the discrete generalized (r, N-r)-fold Darboux transformation is constructed and extended to solve this discrete coupled equation with the fourth-order linear spectral problem, from which diverse exact solutions including usual multi-soliton and semi-rational soliton solutions on the vanishing background, higher-order rational soliton and mixed hyperbolic-rational soliton solutions on the non-vanishing background are derived, and the limit states of some soliton and rational soliton solutions are analyzed by the asymptotic analysis technique. Finally, the numerical simulations are used to explore the dynamical behaviors of some exact soliton solutions. These results may be helpful for understanding some physical phenomena in fields of shallow water wave, optics, and plasma physics.

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Exact solutions of a time-fractional modified KdV equation via bifurcation analysis Min-Yuan Liu(刘敏远), Hui Xu(许慧), and Zeng-Gui Wang(王增桂) Chin. Phys. B, 2023, 32 (12):  120204.  DOI: 10.1088/1674-1056/acf9e8 Abstract ( 103 )   HTML ( 0 )   PDF (1656KB) ( 40 )   The time-fractional modified Korteweg-de Vries (KdV) equation is committed to establish exact solutions by employing the bifurcation method. Firstly, the phase portraits and related qualitative analysis are comprehensively provided. Then, we give parametric expressions of different types of solutions matching with the corresponding orbits. Finally, solution profiles, 3D and density plots of some solutions are presented with proper parametric choices.

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Rational solutions of Painlevé-II equation as Gram determinant Xiaoen Zhang(张晓恩) and Bing-Ying Lu(陆冰滢) Chin. Phys. B, 2023, 32 (12):  120205.  DOI: 10.1088/1674-1056/ad01a5 Abstract ( 115 )   HTML ( 0 )   PDF (648KB) ( 122 )   Under the Flaschka-Newell Lax pair, the Darboux transformation for the Painlevé-II equation is constructed by the limiting technique. With the aid of the Darboux transformation, the rational solutions are represented by the Gram determinant, and then we give the large y asymptotics of the determinant and the rational solutions. Finally, the solution of the corresponding Riemann-Hilbert problem is obtained from the Darboux matrices.

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Preparation of squeezed light with low average photon number based on dynamic Casimir effect Na Li(李娜), Zi-Jian Lin(林资鉴), Mei-Song Wei(韦梅松), Ming-Jie Liao(廖明杰),Jing-Ping Xu(许静平), San-Huang Ke(柯三黄), and Ya-Ping Yang(羊亚平) Chin. Phys. B, 2023, 32 (12):  120301.  DOI: 10.1088/1674-1056/acf2ff Abstract ( 79 )   HTML ( 0 )   PDF (2642KB) ( 27 )   It is well known that squeezed states can be produced by nonlinear optical processes, such as parametric amplification and four wave mixing, in which two photons are created or annihilated simultaneously. Since the Hamiltonian of the dynamic Casimir effect contains a2 and a+2, photons in such a process are also generated or annihilated in pairs. Here we propose to get squeezed light through the dynamic Casimir effect. Specifically, we demonstrate it from the full quantum perspective and the semiclassical perspective successively. Different from previous work, we focus on generating squeezed states with the lowest average photon number, because such squeezed states have better quantum properties. For the full quantum picture, that is, phonons also have quantum properties, when the system is initially in the excited state of phonons, squeezed light cannot be generated during the evolution, but the light field can collapse to the squeezed state by measuring the state of phonons. When the phonon is treated as a classical quantity, that is, the cavity wall is continuously driven, squeezed light with the minimum average photon number will be generated in the case of off-resonance. This will play a positive role in better regulating the photon state generated by the dynamic Casimir system in the future.

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Deep learning framework for time series classification based on multiple imaging and hybrid quantum neural networks Jianshe Xie(谢建设) and Yumin Dong(董玉民) Chin. Phys. B, 2023, 32 (12):  120302.  DOI: 10.1088/1674-1056/accb45 Abstract ( 84 )   HTML ( 0 )   PDF (2350KB) ( 32 )   Time series classification (TSC) has attracted a lot of attention for time series data mining tasks and has been applied in various fields. With the success of deep learning (DL) in computer vision recognition, people are starting to use deep learning to tackle TSC tasks. Quantum neural networks (QNN) have recently demonstrated their superiority over traditional machine learning in methods such as image processing and natural language processing, but research using quantum neural networks to handle TSC tasks has not received enough attention. Therefore, we proposed a learning framework based on multiple imaging and hybrid QNN (MIHQNN) for TSC tasks. We investigate the possibility of converting 1D time series to 2D images and classifying the converted images using hybrid QNN. We explored the differences between MIHQNN based on single time series imaging and MIHQNN based on the fusion of multiple time series imaging. Four quantum circuits were also selected and designed to study the impact of quantum circuits on TSC tasks. We tested our method on several standard datasets and achieved significant results compared to several current TSC methods, demonstrating the effectiveness of MIHQNN. This research highlights the potential of applying quantum computing to TSC and provides the theoretical and experimental background for future research.

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Parameterized monogamy and polygamy relations of multipartite entanglement Zhong-Xi Shen(沈中喜), Ke-Ke Wang(王珂珂), and Shao-Ming Fei(费少明) Chin. Phys. B, 2023, 32 (12):  120303.  DOI: 10.1088/1674-1056/acf300 Abstract ( 77 )   HTML ( 0 )   PDF (635KB) ( 23 )   Monogamy and polygamy relations are important properties of entanglement, which characterize the entanglement distribution of multipartite systems. We explore monogamy and polygamy relations of entanglement in multipartite systems by using two newly derived parameterized mathematical inequalities, and establish classes of parameterized monogamy and polygamy relations of multiqubit entanglement in terms of concurrence and entanglement of formation. We show that these new parameterized monogamy and poelygamy inequalities are tighter than the existing ones by detailed examples.

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Performance of entanglement-assisted quantum codes with noisy ebits over asymmetric and memory channels Ji-Hao Fan(樊继豪), Pei-Wen Xia(夏沛文), Di-Kang Dai(戴迪康), and Yi-Xiao Chen(陈一骁) Chin. Phys. B, 2023, 32 (12):  120304.  DOI: 10.1088/1674-1056/acf492 Abstract ( 76 )   HTML ( 0 )   PDF (5444KB) ( 17 )   Entanglement-assisted quantum error correction codes (EAQECCs) play an important role in quantum communications with noise. Such a scheme can use arbitrary classical linear code to transmit qubits over noisy quantum channels by consuming some ebits between the sender (Alice) and the receiver (Bob). It is usually assumed that the preshared ebits of Bob are error free. However, noise on these ebits is unavoidable in many cases. In this work, we evaluate the performance of EAQECCs with noisy ebits over asymmetric quantum channels and quantum channels with memory by computing the exact entanglement fidelity of several EAQECCs. We consider asymmetric errors in both qubits and ebits and show that the performance of EAQECCs in entanglement fidelity gets improved for qubits and ebits over asymmetric channels. In quantum memory channels, we compute the entanglement fidelity of several EAQECCs over Markovian quantum memory channels and show that the performance of EAQECCs is lowered down by the channel memory. Furthermore, we show that the performance of EAQECCs is diverse when the error probabilities of qubits and ebits are different. In both asymmetric and memory quantum channels, we show that the performance of EAQECCs is improved largely when the error probability of ebits is reasonably smaller than that of qubits.

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Controlling stationary one-way steering in a three-level atomic ensemble Jie Peng(彭洁), Jun Xu(徐俊), Hua-Zhong Liu(刘华忠), and Zhang-Li Lai(赖章丽) Chin. Phys. B, 2023, 32 (12):  120305.  DOI: 10.1088/1674-1056/acf82b Abstract ( 68 )   HTML ( 0 )   PDF (1717KB) ( 18 )   We propose a scheme for establishing the stationary one-way quantum steering in a three-level Λ-type atomic ensemble. In our system, the cavity modes are generated from two atomic dipole-allowed transitions, which are in turn driven by two external classical fields. The atomic ensemble can act as an engineered reservoir to put two cavity modes into a squeezed state by two Bogoliubov dissipation pathways. When the damping rates of the two cavity modes are different, the steady-state one-way quantum steering of the intracavity and output fields is presented by adjusting the normalized detuning. The physical mechanism is analyzed based on a dressed state representation and Bogoliubov mode transformation. The achieved optical one-way quantum steering scheme has potential applications in quantum secret information sharing protocols.

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Compact generation scheme of path-frequency hyperentangled photons using 2D periodical nonlinear photonic crystal Yang-He Chen(陈洋河), Bo Ji(季波), Nian-Qin Li(李念芹), Zhen Jiang(姜震), Wei Li(李维),Yu-Dong Li(李昱东), Liang-Sen Feng(冯梁森), Teng-Fei Wu(武腾飞), and Guang-Qiang He(何广强) Chin. Phys. B, 2023, 32 (12):  120307.  DOI: 10.1088/1674-1056/ad0625 Abstract ( 89 )   HTML ( 0 )   PDF (1009KB) ( 32 )   Hyperentanglement is a promising resource for achieving high capacity quantum communication. Here, we propose a compact scheme for the generation of path-frequency hyperentangled photon pairs via spontaneous parametric down-conversion (SPDC) processes, where six different paths and two different frequencies are covered. A two-dimensional periodical χ(2) nonlinear photonic crystal (NPC) is designed to satisfy type-I quasi-phase-matching conditions in the plane perpendicular to the incident pump beam, and a perfect phase match is achieved along the pump beam's direction to ensure high conversion efficiency, with theoretically estimated photon flux up to 2.068×105 pairs·s-1·mm-2. We theoretically calculate the joint-spectral amplitude (JSA) of the generated photon pair and perform Schmidt decomposition on it, where the resulting entropy S of entanglement and effective Schmidt rank K reach 3.2789 and 6.4675, respectively. Our hyperentangled photon source scheme could provide new avenues for high-dimensional quantum communication and high-speed quantum information processing.

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Darboux transformation, infinite conservation laws, and exact solutions for the nonlocal Hirota equation with variable coefficients Jinzhou Liu(刘锦洲), Xinying Yan(闫鑫颖), Meng Jin(金梦), and Xiangpeng Xin(辛祥鹏) Chin. Phys. B, 2023, 32 (12):  120401.  DOI: 10.1088/1674-1056/acf703 Abstract ( 79 )   HTML ( 0 )   PDF (1667KB) ( 16 )   This article presents the construction of a nonlocal Hirota equation with variable coefficients and its Darboux transformation. Using zero-seed solutions, 1-soliton and 2-soliton solutions of the equation are constructed through the Darboux transformation, along with the expression for N-soliton solutions. Influence of coefficients that are taken as a function of time instead of a constant, i.e., coefficient function δ(t), on the solutions is investigated by choosing the coefficient function δ(t), and the dynamics of the solutions are analyzed. This article utilizes the Lax pair to construct infinite conservation laws and extends it to nonlocal equations. The study of infinite conservation laws for nonlocal equations holds significant implications for the integrability of nonlocal equations.

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The Reissner-Nordström black hole surrounded by quintessence may not be destroyed Hao Tang(唐浩) and Jia Zhang(张甲) Chin. Phys. B, 2023, 32 (12):  120402.  DOI: 10.1088/1674-1056/acd620 Abstract ( 79 )   HTML ( 0 )   PDF (828KB) ( 21 )   In the study of weak cosmic censorship conjectures (WCCC), some research finds that the Reissner-Nordström black hole might be destroyed by a test particle with particular mass and charge under some conditions, which means that the naked singularity of the black hole could be observed. This is not allowed in WCCC. We have never observed such naked singularities which should not exist in theory, so we need to find a proper way to protect the black hole from being destroyed by such particles. In this paper, we study a Reissner-Nordström black hole that is surrounded by quintessence (RN-Q) and find that the black hole would be stable and safe because of the effective potential barrier induced by the quintessence term. This result may also show in a sense that the quintessence might have more potential value.

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Temperature-induced logical resonance in the Hodgkin-Huxley neuron Haiyou Deng(邓海游), Rong Gui(桂容), and Yuangen Yao(姚元根) Chin. Phys. B, 2023, 32 (12):  120501.  DOI: 10.1088/1674-1056/accd49 Abstract ( 100 )   HTML ( 0 )   PDF (1083KB) ( 51 )   Logical resonance has been demonstrated to be present in the FitzHugh-Nagumo (FHN) neuron, namely, the FHN neuron can operate as a reliable logic gate within an optimal parameter window. Here we attempt to extend the results to the more biologically realistic Hodgkin-Huxley (HH) model of neurons. In general, biological organisms have an optimal temperature at which the biological functions are most effective. In view of this, we examine if there is an optimal range of temperature where the HH neuron can work like a specific logic gate, and how temperature influences the logical resonance. Here we use the success probability P to measure the reliability of the specific logic gate. For AND logic gate, P increases with temperature T, reaches the maximum in an optimal window of T, and eventually decreases, which indicates the occurrence of the temperature-induced logical resonance phenomenon in the HH neuron. Moreover, single and double logical resonances can be induced by altering the frequency of the modulating periodic signal under the proper temperatures, suggesting the appearance of temperature-controlled transition of logical resonance. These results provide important clues for constructing neuron-based energy-efficient new-fashioned logical devices.

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Team-based fixed-time containment control for multi-agent systems with disturbances Xiao-Wen Zhao(赵小文), Jin-Yue Wang(王进月), Qiang Lai(赖强), and Yuan Liu(刘源) Chin. Phys. B, 2023, 32 (12):  120502.  DOI: 10.1088/1674-1056/aceeeb Abstract ( 73 )   HTML ( 0 )   PDF (1184KB) ( 24 )   We investigate the fixed-time containment control (FCC) problem of multi-agent systems (MASs) under discontinuous communication. A saturation function is used in the controller to achieve the containment control in MASs. One difference from using a symbolic function is that it avoids the differential calculation process for discontinuous functions, which further ensures the continuity of the control input. Considering the discontinuous communication, a dynamic variable is constructed, which is always non-negative between any two communications of the agent. Based on the designed variable, the dynamic event-triggered algorithm is proposed to achieve FCC, which can effectively reduce controller updating. In addition, we further design a new event-triggered algorithm to achieve FCC, called the team-trigger mechanism, which combines the self-triggering technique with the proposed dynamic event trigger mechanism. It has faster convergence than the proposed dynamic event triggering technique and achieves the tradeoff between communication cost, convergence time and number of triggers in MASs. Finally, Zeno behavior is excluded and the validity of the proposed theory is confirmed by simulation.

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Different wave patterns for two-coupled Maccari's system with complex structure via truncated Painlevé approach Hongcai Ma(马红彩), Xinru Qi(戚心茹), and Aiping Deng(邓爱平) Chin. Phys. B, 2023, 32 (12):  120503.  DOI: 10.1088/1674-1056/acf497 Abstract ( 105 )   HTML ( 0 )   PDF (2693KB) ( 67 )   We focused on the two-coupled Maccari's system. With the help of truncated Painlevé approach (TPA), we express local solution in the form of arbitrary functions. From the solution obtained, using its appropriate arbitrary functions, we have generated the rogue wave pattern solutions, rogue wave solutions, and lump solutions. In addition, by controlling the values of the parameters in the solutions, we show the dynamic behaviors of the rogue wave pattern solutions, rogue wave solutions, and lump solutions with the aid of Maple tool. The results of this study will contribute to the understanding of nonlinear wave dynamics in higher dimensional Maccari's systems.

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Surface lattice resonance of circular nano-array integrated on optical fiber tips Jian Wu(吴坚), Gao-Jie Ye(叶高杰), Xiu-Yang Pang(庞修洋), Xuefen Kan(阚雪芬), Yan Lu(陆炎), Jian Shi(史健), Qiang Yu(俞强), Cheng Yin(殷澄), and Xianping Wang(王贤平) Chin. Phys. B, 2023, 32 (12):  120701.  DOI: 10.1088/1674-1056/acf491 Abstract ( 103 )   HTML ( 0 )   PDF (2861KB) ( 29 )   As metallic nanoparticles are arranged to form a 2D periodic nano-array, the coupling of the localized surface plasmonic resonance (LSPR) results in the well-known phenomenon of surface lattice resonances (SLRs). We theoretically investigate the SLR effect of the circular nano-array fabricated on the fiber tips. The difference between the 2D periodic and circular periodic arrays results in different resonant characteristics. For both structures, the resonant peaks due to the SLRs shift continuously as the array structures are adjusted. For some specific arrangements, the circular nano-array may generate a single sharp resonant peak with extremely high enhancement, which originates from the collective coupling of the whole array. More interestingly, the spatial pattern of the vector near-field corresponding to the sharp peak is independent of the polarization state of the incidence, facilitating its excitation and regulation. This finding may be helpful for designing multifunctional all-fiber devices.

ATOMIC AND MOLECULAR PHYSICS

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Revising the H216O line-shape parameters around 1.1 μm based on the speed-dependent Nelkin-Ghatak profile and the Hartmann-Tran profile Hui Zhang(张惠), Jianjie Zheng(郑健捷), Qiang Liu(刘强), Wenyue Zhu(朱文越), Xianmei Qian(钱仙妹), Guisheng Jiang(江贵生), Shenlong Zha(查申龙), Qilei Zhang(张启磊), and Hongliang Ma(马宏亮) Chin. Phys. B, 2023, 32 (12):  123301.  DOI: 10.1088/1674-1056/acc7f5 Abstract ( 92 )   HTML ( 0 )   PDF (1503KB) ( 17 )   Accurate spectroscopic data for H216O in the 1.1 μ m region are particularly important for the study of Earth's atmosphere. The pure water vapor molecular spectra were measured based on direct laser absorption spectroscopy using a narrow line-width external cavity diode laser combined with a high-precision Fabry-Pérot etalon. A total of 31 H216O transitions were studied for the first time by using the speed-dependent Nelkin-Ghatak profile and the Hartmann-Tran profile. From an accurate line-shape analysis, we obtained the line intensities and the self-broadening coefficients, and they are compared with the available data reported in the HITRAN 2016 database and the HITRAN 2020 database. Finally, we obtained information on the influence of Dicke narrowing, as well as the correlations between Dicke narrowing and speed dependence, and of speed-dependent effects.

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Mixed-field effect at the hyperfine level of 127I79Br in its rovibronic ground state: Toward field manipulation of cold molecules Zhengbin Bao(包正斌), Defu Wang(王得富), Xuping Shao(邵旭萍),Yunxia Huang(黄云霞), and Xiaohua Yang(杨晓华) Chin. Phys. B, 2023, 32 (12):  123302.  DOI: 10.1088/1674-1056/ace61c Abstract ( 88 )   HTML ( 0 )   PDF (901KB) ( 14 )   The mixed-field effect at the hyperfine level of the rovibronic ground state of the 127I79Br (X1Σ, v = 0, J = 0) molecule is computed on the J-I uncoupled basis of |JMJI1M1I2M2>, where J is the molecular total angular momentum excluding nuclear spin, MJ is the projection number of J, I1 and I2 are the nuclear spins of the iodine and bromine atoms, and M1 and M2 are the projection numbers of I1 and I2, respectively. When the two applied electric and magnetic fields are parallel, the perturbations are rare and only one perturbation is observed in a relatively large field regime in our computation range. However, when the two fields are off-parallel, the perturbations increase significantly and some sublevels show the Feshbach-like resonance phenomenon. Therefore, such sublevels transit between weak-field seeking and strong-field seeking repeatedly, which can be utilized to enhance or suppress cold molecular collision and chemical reaction rates. Such behavior of the molecular hyperfine structure in the mixed off-parallel fields may also be utilized to construct an electric-field-assisted anti-Helmholtz magnetic trap for cold molecules and to realize evaporative cooling of cold molecules (sub-mK) into the ultracold regime (μK).

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

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Tailoring topological corner states in photonic crystals by near- and far-field coupling effects Zhao-Jian Zhang(张兆健), Zhi-Hao Lan(兰智豪), Huan Chen(陈欢), Yang Yu(于洋), and Jun-Bo Yang(杨俊波) Chin. Phys. B, 2023, 32 (12):  124201.  DOI: 10.1088/1674-1056/acddd3 Abstract ( 94 )   HTML ( 0 )   PDF (1702KB) ( 28 )   We explore the behaviors of optically coupled topological corner states in supercell arrays composed of photonic crystal rods, where each supercell is a second-order topological insulator. Our findings indicate that the coupled corner states possess nondegenerate eigenfrequencies at the Γ point, with coupled dipole corner states excited resonantly by incident plane waves and displaying a polarization-independent characteristic. The resonance properties of coupled dipole corner states can be effectively modulated via evanescently near-field coupling, while multipole decomposition shows that they are primarily dominated by electric quadrupole moment and magnetic dipole moment. Furthermore, we demonstrate that these coupled corner states can form surface lattice resonances driven by diffractively far-field coupling, leading to a dramatic increase in the quality factor. This work introduces more optical approaches to tailoring photonic topological states, and holds potential applications in mid-infrared topological micro-nano devices.

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Enhancement of the group delay in quadratic coupling optomechanical systems subjected to an external force Jimmi Hervé Talla Mbé, Ulrich Chancelin Tiofack Demanou, Christian Kenfack-Sadem, and Martin Tchoffo Chin. Phys. B, 2023, 32 (12):  124202.  DOI: 10.1088/1674-1056/accc80 Abstract ( 88 )   HTML ( 0 )   PDF (848KB) ( 26 )   We theoretically study the effect of the quadratic coupling strength on optomechanical systems subjected to a continuous external force. Quadratic coupling strength originates from strong coupling between the optical and the mechanical degrees of freedom. We show that the quadratic coupling strength reduces the amplitude of the dispersion spectra at the resonance in both {blue- and red-sideband regimes}. However, it increases (decreases) the amplitude of the absorption spectrum in the blue- (red-)sideband regime. Furthermore, in both sideband regimes, the effective detuning between the pump and the cavity deviates with the quadratic coupling strength. Thereby, appropriate selection of the quadratic coupling strength results in an important magnification (in absolute value) of the group delay for both slow and fast light exiting from the optomechanical cavity.

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Dynamic modulated single-photon routing Hao-Zhen Li(李浩珍), Ran Zeng(曾然), Miao Hu(胡淼), Mengmeng Xu(许蒙蒙), Xue-Fang Zhou(周雪芳), Xiuwen Xia(夏秀文), Jing-Ping Xu(许静平), and Ya-Ping Yang(羊亚平) Chin. Phys. B, 2023, 32 (12):  124203.  DOI: 10.1088/1674-1056/acf662 Abstract ( 93 )   HTML ( 0 )   PDF (2004KB) ( 116 )   The dynamic control of single-photon scattering in a pair of one-dimensional waveguides mediated by a time-modulated atom-cavity system is investigated. Two cases, where the waveguides are coupled symmetrically or asymmetrically to the atom-cavity system, are discussed in detail. The results show that such time-modulated atom-cavity configuration can behave as a dynamical tunable directional single-photon router. The photons with different frequencies can dynamically be routed from the incident waveguide into any ports of the other with a 100% probability via adjusting the modulated amplitude or phases of the time-modulated atom-cavity coupling strengths, associate with the help of the asymmetrical waveguide-cavity couplings. Furthermore, the influence of dissipation on the routing capability is investigated. It is shown that the present single-photon router is robust against the dissipative process of the system, especially the atomic dissipation. These results are expected to be applicable in quantum information processing and design quantum devices with dynamical modulation.

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Multi-channel terahertz focused beam generator based on shared-aperture metasurface Jiu-Sheng Li(李九生) and Yi Chen(陈翊) Chin. Phys. B, 2023, 32 (12):  124204.  DOI: 10.1088/1674-1056/acddd2 Abstract ( 81 )   HTML ( 0 )   PDF (1921KB) ( 55 )   Most of existing metasurfaces usually have limited channel behavior, which seriouslyhinders their development and application. In this paper, we propose a multi-channel terahertz focused beam generator based on shared-aperture metasurface, and the generator consists of a top square metal strip, a middle layer of silica and a metal bottom plate. By changing the position and size of the shared-aperture array, the designed metasurface can generate any number of multi-channel focusing beams at different predicted positions. In addition, the energy intensity of focusing beams can be controlled. The full-wave simulation results show that the metasurface achieves four-channel vortex focused beam generation with different topological charges, and five-, six-, eight-channel focused beam generation with different energy intensities at a frequency of 1 THz, which are in good agreement with the theoretically calculated predictions. This work can provide a new idea for designing the terahertz multichannel devices.

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Laser parameters affecting the asymmetric radiation of the electron in tightly focused intense laser pulses Xing-Yu Li(李星宇), Wan-Yu Xia(夏婉瑜), You-Wei Tian(田友伟), and Shan-Ling Ren(任山令) Chin. Phys. B, 2023, 32 (12):  124205.  DOI: 10.1088/1674-1056/acd3dd Abstract ( 73 )   HTML ( 0 )   PDF (4282KB) ( 24 )   The nonlinear radiation of the electron is a distinctive feature of the action of tightly focused linearly polarized lasers. In this paper, from the perspective of radiation symmetry, the effect of laser parameters on the electron radiation power in the time domain is studied systematically. An asymmetric bimodal structure is found in the time domain in the direction of the maximum radiation. For this special structure, an explanation is given based on the electron dynamics perspective. The structure is compared with the symmetric bimodal structure in the classical theory. The increase in laser intensity, while significantly increasing the radiated power of the electron, exacerbates the asymmetry of the electron radiation. The variation in the initial phase of the laser leads to a periodic variation in the electron motion, which results in a periodic extension of the electron spatial radiation with a period of π. Moreover, the existence of jump points with a phase difference of π in the range of 0-2π is found. The increase in pulse width reduces the radiated power, extends the radiation range, and alleviates the radiation asymmetry. The results in this paper contribute to the study of electron radiation characteristics in intense laser fields.

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Time-dependent variational approach to solve multi-dimensional time-dependent Schrödinger equation Mingrui He(何明睿), Zhe Wang(王哲), Lufeng Yao(姚陆锋), and Yang Li(李洋) Chin. Phys. B, 2023, 32 (12):  124206.  DOI: 10.1088/1674-1056/acef03 Abstract ( 94 )   HTML ( 0 )   PDF (938KB) ( 27 )   We present an efficient approach to solve multi-dimensional time-dependent Schrödinger equation (TDSE) in an intense laser field. In this approach, each spatial degree of freedom is treated as a distinguishable quasi-particle. The non-separable Coulomb potential is regarded as a two-body operator between different quasi-particles. The time-dependent variational principle is used to derive the equations of motion. Then the high-order multi-dimensional problem is broken down into several lower-order coupled equations, which can be efficiently solved. As a demonstration, we apply this method to solve the two-dimensional TDSE. The accuracy is tested by comparing the direct solutions of TDSE using several examples such as the strong-field ionization and the high harmonic generation. The results show that the present method is much more computationally efficient than the conventional one without sacrificing accuracy. The present method can be straightforwardly extended to three-dimensional problems. Our study provides a flexible method to investigate the laser-atom interaction in the nonperturbative regime.

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Generation of structure light in probe absorption spectrum via microwave-driven Y-type atomic system Muhammad Saeed and Muqaddar Abbas Chin. Phys. B, 2023, 32 (12):  124211.  DOI: 10.1088/1674-1056/aceee7 Abstract ( 97 )   HTML ( 0 )   PDF (1367KB) ( 87 )   Behavior of structure light is investigated by monitoring probe absorption using a microwave-driven Y-type atomic media configuration. The system under consideration is driven by one of the control vortex beams as well as an extra non-vortex control beam to ensure electromagnetically induced transparency. The significant aspect in the generation of structured light is the azimuthal phase-dependent modification for probe absorption. Further intensity distribution for absorption spectra is examined for simultaneously evaluating both the control vortex beams. We also go through the radial distribution of intensity for various orbital angular momentum values. Different modes of structural beams may be distinguished using the suggested approach. Our research gives us a way for rapidly transferring vortex wavefronts from control field to probe absorption profile. This could be useful in quantum information processing.

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Spin splitting of vortex beams on the surface of natural biaxial hyperbolic materials Hong Liang(梁红), Haoyuan Song(宋浩元), Yubo Li(李宇博), Di Yu(于迪), and Shufang Fu(付淑芳) Chin. Phys. B, 2023, 32 (12):  124212.  DOI: 10.1088/1674-1056/ad0ccc Abstract ( 82 )   HTML ( 0 )   PDF (2250KB) ( 22 )   We investigated the spin splitting of vortex beam on the surface of biaxial natural hyperbolic materials (NHMs) rotated by an angle with respect to the incident plane. An obvious asymmetry of spatial shifts produced by the left-handed circularly (LCP) component and right-handed circularly polarized (RCP) component is exhibited. We derived the analytical expression for in- and out-of-plane spatial shifts for each spin component of the vortex beam. The orientation angle of the optical axis plays a key role in the spin splitting between the two spin components, which can be reflected in the simple expressions for spatial shifts without the rotation angle. Based on an α-MoO3 biaxial NHM, the spatial shifts of the two spin components with the topological charge were investigated. As the topological charge increases, the spatial shifts also increase; in addition, a tiny spatial shift close to zero can be obtained if we control the incident frequency or the polarization of the reflected beams. It can also be concluded that the maximum of the spin splitting results from the LCP component at p-incidence and the RCP component at s-incidence in the RB-II hyperbolic frequency band. The effect of the incident angle and the thickness of the α-MoO3 film on spin splitting is also considered. These results can be used for manipulating infrared radiation and optical detection.

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Fast estimation of distance between two hydrophones using ocean ambient noise in multi-ship scenarios Xuefeng Liu(刘雪枫), Zhi Xia(夏峙), Qi Li(李琪), and Ye Ding(丁烨) Chin. Phys. B, 2023, 32 (12):  124301.  DOI: 10.1088/1674-1056/acf91b Abstract ( 76 )   HTML ( 0 )   PDF (3498KB) ( 19 )   Accurately estimating the bearing of a target with two hydrophones requires knowing the precise distance between them. However, in practice, it is difficult to measure this distance accurately due to the influence of current. To solve this problem, we propose a method for extracting the time-domain Green's function between two points in multi-ship scenarios and for extracting the time-domain waveform arrival structure between two hydrophones in real-time based on long samples of ship radiation noise cross-correlation. Using the cross-correlation function of the radiated noise from any ship located in the end-fire direction of the two hydrophones, we can estimate the distance between the hydrophones in real-time. To verify the accuracy of our estimation, we compare the result of azimuth estimation with the actual azimuth based on the azimuth estimation of a cooperative sound source in the maritime environment. Our experimental results show that the proposed method correctly estimates the distance between two hydrophones that cannot be directly measured and estimates the position of a cooperative sound source 4 km away with an average deviation of less than 1.2°.

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Energy-distributable waterborne acoustic launcher for directional sensing Tian Yang(杨天), Wenting Gao(高文婷), Shida Fan(范世达), Jie Ren(任捷), and Tianzhi Yang(杨天智) Chin. Phys. B, 2023, 32 (12):  124302.  DOI: 10.1088/1674-1056/acf5cf Abstract ( 76 )   HTML ( 1 )   PDF (5257KB) ( 14 )   Highly directional launch and intensity adjustment of underwater acoustic signals are crucial in many areas such as abyssal navigation, underwater signal communication, and detection for marine biology. Inspired by the phenomenon that aquatic animals like dolphins detect and track prey with high resolution, we propose an energy-distributable directional sensing strategy which can achieve parallel needle-like transmitting sound beams with adjustable energy based on out-coupling valley-polarized edge states. The acoustic spin angular momentum and energy flow distribution at different interfaces inside the phononic crystal are provided and they show tight coupling. Furthermore, a sound beam with a width of 20° and an acoustic intensity enhancement factor ≈6.6 are observed in the far field. As an application, we show that this device can be used as an acoustic energy distributor. This communication pattern with excellent functionalities and performance provides a desirable idea for high-energy-level directional collimated underwater sensing and underwater acoustic energy distribution.

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Ultra-broadband acoustic ventilation barrier based on multi-cavity resonators Yu-Wei Xu(许雨薇), Yi-Jun Guan(管义钧), Cheng-Hao Wu(吴成昊), Yong Ge(葛勇), Qiao-Rui Si(司乔瑞), Shou-Qi Yuan(袁寿其), and Hong-Xiang Sun(孙宏祥) Chin. Phys. B, 2023, 32 (12):  124303.  DOI: 10.1088/1674-1056/acf5d1 Abstract ( 88 )   HTML ( 0 )   PDF (1917KB) ( 36 )   The numerical simulations and experimental results of an ultra-broadband acoustic ventilation barrier composed of periodic unit cells are reported in this paper. Based on multiple mechanisms, including sound absorption by eigenmodes of the unit cell and sound reflection by a plate structure on upper surface of the unit cell, a single-layer ventilation barrier with broadband sound reduction is designed, and its working bandwidth can reach about 1560 Hz. The experimental results accord well with the simulation results. Furthermore, two types of three-layer ventilation barriers are designed and demonstrated by using the unit cells with different values of a(the length of the hollow square region) and w(the width of the channel between the adjacent cavities), and the bandwidths of both ventilation barriers can increase to 3160 Hz and 3230 Hz, respectively. The designed barrier structures have the advantages of ultra-broadband sound reduction and ventilation, which paves the way to designing high-performance ventilation barriers for the applications in environmental protection and architectural acoustics.

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Reconstructions of time-evolving sound-speed fields perturbed by deformed and dispersive internal solitary waves in shallow water Qin-Ran Li(李沁然), Chao Sun(孙超), Lei Xie(谢磊), and Xiao-Dong Huang(黄晓冬) Chin. Phys. B, 2023, 32 (12):  124701.  DOI: 10.1088/1674-1056/acf84d Abstract ( 96 )   HTML ( 1 )   PDF (1998KB) ( 20 )   The high-fidelity reconstruction of sound speeds is crucial for predicting acoustic propagation in shallow water where internal solitary waves (ISWs) are prevalent. Mapping temperatures from time series to spatial fields is an approach widely used to reproduce the sound speed perturbed by deformed internal waves. However, wave-shape distortions are inherent in the modeling results. This paper analyzes the formation mechanism and dynamic behavior of the distorted waveform that is shown to arise from the mismatch between the modeled and real propagation speeds of individual solitons within an ISW packet. To mitigate distortions, a reconstruction method incorporating the dispersion property of an ISW train is proposed here. The principle is to assign each soliton a real speed observed in the experiment. Then, the modeled solitons propagate at their intrinsic speeds, and the packet disperses naturally with time. The method is applied to reconstruct the sound speed perturbed by ISWs in the South China Sea. The mean and median of the root-mean-square error between the reconstructed and measured sound speeds are below 2 m/s. The modeled shape deformations and packet dispersion agree well with observations, and the waveform distortion is reduced compared with the original method. This work ensures the high fidelity of waveguide-environment reconstructions and facilitates the investigation of sound propagation in the future.

PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

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The (1+1)-dimensional nonlinear ion acoustic waves in multicomponent plasma containing kappa electrons Mai-Mai Lin(林麦麦), Lei Jiang(蒋蕾), and Ming-Yue Wang(王明月) Chin. Phys. B, 2023, 32 (12):  125201.  DOI: 10.1088/1674-1056/ace8f9 Abstract ( 95 )   HTML ( 0 )   PDF (973KB) ( 16 )   Large amplitude (1+1)-dimensional nonlinear ion acoustic waves are theoretically studied in multicomponent plasma consisting of positively charged ions and negatively charged ions, ion beam, kappa-distributed electrons, and dust grains, respectively. By using the Sagdeev potential method, the dynamical system and the Sagdeev potential function are obtained. The important influences of system parameters on the phase diagram of this system are investigated. It is found that the linear waves, the nonlinear waves and the solitary waves are coexistent in the multicomponent plasma system. Meanwhile, the variations of Sagdeev potential with parameter can also be obtained. Finally, it seems that the propagating characteristics of (1+1)-dimensional nonlinear ion acoustic solitary waves and ion acoustic nonlinear shock wave can be influenced by different parameters of this system.

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Global simulation of plasma series resonance effect in radio frequency capacitively coupled Ar/O2 plasma Xue Bai(白雪), Hai-Wen Xu(徐海文), Chong-Biao Tian(田崇彪), Wan Dong(董婉), Yuan-Hong Song(宋远红), and You-Nian Wang(王友年) Chin. Phys. B, 2023, 32 (12):  125203.  DOI: 10.1088/1674-1056/ace427 Abstract ( 89 )   HTML ( 0 )   PDF (1012KB) ( 28 )   Radio frequency capacitively coupled plasmas (RF CCPs) play a pivotal role in various applications in etching and deposition processes on a microscopic scale in semiconductor manufacturing. In the discharge process, the plasma series resonance (PSR) effect is easily observed in electrically asymmetric and geometrically asymmetric discharges, which could largely influence the power absorption, ionization rate, etc. In this work, the PSR effect arising from geometrically and electrically asymmetric discharge in argon-oxygen mixture gas is mainly investigated by using a plasma equivalent circuit model coupled with a global model. At relatively low pressures, as Ar content (α) increases, the inductance of the bulk is weakened, which leads to a more obvious PSR phenomenon and a higher resonance frequency (ωpsr). When the Ar content is fixed, varying the pressure and gap distance could also have different effects on the PSR effect. With the increase of the pressure, the PSR frequency shifts towards the higher order, but in the case of much higher pressure, the PSR oscillation would be strongly damped by frequent electron-neutral collisions. With the increase of the gap distance, the PSR frequency becomes lower. In addition, electrically asymmetric waveforms applied to a geometrically asymmetric chamber may weaken or enhance the asymmetry of the discharge and regulate the PSR effect. In this work, the Ar/O2 electronegative mixture gas is introduced in a capacitive discharge to study the PSR effect under geometric asymmetry effect and electrical asymmetry effect, which can provide necessary guidance in laboratory research and current applications.

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Speeding-up direct implicit particle-in-cell simulations in bounded plasma by obtaining future electric field through explicitly propulsion of particles Haiyun Tan(谭海云), Tianyuan Huang(黄天源), Peiyu Ji(季佩宇), Mingjie Zhou(周铭杰), Lanjian Zhuge(诸葛兰剑), and Xuemei Wu(吴雪梅) Chin. Phys. B, 2023, 32 (12):  125204.  DOI: 10.1088/1674-1056/acf449 Abstract ( 85 )   HTML ( 0 )   PDF (1103KB) ( 50 )   The direct implicit particle-in-cell is a powerful kinetic method for researching plasma characteristics. However, it is time-consuming to obtain the future electromagnetic field in such a method since the field equations contain time-dependent matrix coefficients. In this work, we propose to explicitly push particles and obtain the future electromagnetic field based on the information about the particles in the future. The new method retains the form of implicit particle pusher, but the future field is obtained by solving the traditional explicit equation. Several numerical experiments, including the motion of charged particle in electromagnetic field, plasma sheath, and free diffusion of plasma into vacuum, are implemented to evaluate the performance of the method. The results demonstrate that the proposed method can suppress finite-grid-instability resulting from the coarse spatial resolution in electron Debye length through the strong damping of high-frequency plasma oscillation, while accurately describe low-frequency plasma phenomena, with the price of losing the numerical stability at large time-step. We believe that this work is helpful for people to research the bounded plasma by using particle-in-cell simulations.

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Numerical simulation study of ionization characteristics of argon dielectric barrier discharge Guiming Liu(刘桂铭), Lei Chen(陈雷), Zhibo Zhao(赵智博), and Peng Song(宋鹏) Chin. Phys. B, 2023, 32 (12):  125205.  DOI: 10.1088/1674-1056/acc0f8 Abstract ( 81 )   HTML ( 0 )   PDF (1930KB) ( 14 )   In order to better analyze the characteristics of particle distribution and its influencing factors in the ionized space during the process of coaxial dielectric barrier discharge, a self-designed two-dimensional axisymmetric structure exciter was used to carry out optical diagnosis, with the electron temperature calculated through Gaussian fitting. A plasma model was applied to conduct research on the discharge process through numerical simulation, with the changes in electron density and electron temperature were analyzed by using different discharge parameters. The research results show that with an increase in discharge voltage, pressure inside the reactor and relative permittivity, the discharge process is promoted. In addition, a rise in current density leads to an increase in the number of charged particles on the surface of the medium during the discharge process, while a rise in discharge intensity causes an increase in the electron density. Electron temperature decreases due to the increased loss of collision energy between particles. These results were confirmed by comparing experimental data with simulation results.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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Structural stability and ion migration of Li2MnO3 cathode material under high pressures Ze-Ren Xie(谢泽仁), Si-Si Zhou(周思思), Bei-Bei He(贺贝贝), Huan-Wen Wang(王欢文), Yan-Sheng Gong(公衍生), Jun Jin(金俊), Xiang-Gong Zhang(张祥功), and Rui Wang(汪锐) Chin. Phys. B, 2023, 32 (12):  126101.  DOI: 10.1088/1674-1056/ace2b1 Abstract ( 83 )   HTML ( 0 )   PDF (1053KB) ( 59 )   Some special fields, such as deep-sea exploration, require batteries and their electrode materials to withstand extremely high pressure. As the cathode material has the highest energy density, Li-excess Mn-based materials are also likely to be utilized in such an environment. However, the effect of pressure on the crystal structure and migration barrier of this kind of material is still not clear at present. Therefore, in this study, we investigate the properties of the matrix material of Li-excess Mn-based material, Li2MnO3, under high pressure. The equation of state, bulk modulus, and steady-state volume of Li2MnO3 are predicted by the method of first principles calculation. The calculations of unit cells at different pressures reveal that the cell parameters suffer anisotropic compression under high pressure. During compression, Li-O bond is more easily compressed than Mn-O bond. The results from the climbing image nudged elastic band (CINEB) method show that the energy barrier of Li+ migration in the lithium layer increases with pressure increasing. Our study can provide useful information for utilizing Li-excess Mn-based materials under high pressure.

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Direct observation of the distribution of impurity in phosphorous/boron co-doped Si nanocrystals Dongke Li(李东珂), Junnan Han(韩俊楠), Teng Sun(孙腾), Jiaming Chen(陈佳明), Etienne Talbot, Rémi Demoulin, Wanghua Chen(陈王华), Xiaodong Pi(皮孝东), Jun Xu(徐骏), and Kunji Chen(陈坤基) Chin. Phys. B, 2023, 32 (12):  126102.  DOI: 10.1088/1674-1056/acd7cf Abstract ( 80 )   HTML ( 0 )   PDF (1229KB) ( 54 )   Doping in Si nanocrystals is an interesting topic and directly studying the distribution of dopants in phosphorous/boron co-doping is an important issue facing the scientific community. In this study, atom probe tomography is performed to study the structures and distribution of impurity in phosphorous/boron co-doped Si nanocrystals/SiO2 multilayers. Compared with phosphorous singly doped Si nanocrystals, it is interesting to find that the concentration of phosphorous in co-doped samples can be significantly improved. Theoretical simulation suggests that phosphorous-boron pairs are formed in co-doped Si nanocrystals with the lowest formation energy, which also reduces the formation energy of phosphorous in Si nanocrystals. The results indicate that co-doping can promote the entry of phosphorous impurities into the near-surface and inner sites of Si nanocrystals, which provides an interesting way to regulate the electronic and optical properties of Si nanocrystals such as the observed enhancement of conductivity and sub-band light emission.

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Rolling structure from bilayer nanofilm by mismatch Jian-Gang Li(李建刚), Xiao-Pi Geng(耿小丕), Qian-Nan Gao(高倩男), Jun Zhu(朱俊), Zhi-Xiang Gao(高志翔), and Hong-Wei Zhu(朱弘伟) Chin. Phys. B, 2023, 32 (12):  126201.  DOI: 10.1088/1674-1056/ace032 Abstract ( 68 )   HTML ( 0 )   PDF (734KB) ( 17 )   A continuum theoretical scheme for self-rolling nanotubes from bilayers by mismatch is obtained by considering surface elasticity, surface stress, and symmetry lowering effects. For an ultrathin nanofilm with only several nanometers in thickness, isotropic mismatch, and isotropic surface stress usually induce anisotropic rolling behavior. The isotropic Timoshenko formula should be modified anisotropically to explain the mechanical behavior of anisotropic rolling structure of nanotubes accurately. The nanofilm rolls up in tangential direction while remaining straight in cylindrical direction theoretically. Therefore, in this paper the anisotropic shape of nanotubes is taken into consideration. Along the cylindrical direction, although it maintains straight and its residual strain is uniform, the stress varies in the radial direction due to the Poisson's effect of tangential strain. The results of the current theory applied to Si-Si nanotube, InAs-GaAs nanotube, and InGaAs-Cr nanotube systems show good agreement with the experimental data. Beside the surface elasticity effect and surface stress effect, the symmetry breaking and the anisotropic rolling structure are of great importance in theoretically describing the mechanical behavior of rolling-up of nanotubes.

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

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In-plane uniaxial-strain tuning of superconductivity and charge-density wave in CsV3Sb5 Hot! Xiaoran Yang(杨晓冉), Qi Tang(唐绮), Qiuyun Zhou(周秋韵), Huaiping Wang(王怀平), Yi Li(李意), Xue Fu(付雪), Jiawen Zhang(张加文), Yu Song(宋宇), Huiqiu Yuan(袁辉球), Pengcheng Dai(戴鹏程), and Xingye Lu(鲁兴业) Chin. Phys. B, 2023, 32 (12):  127101.  DOI: 10.1088/1674-1056/acf707 Abstract ( 303 )   HTML ( 0 )   PDF (1831KB) ( 340 )   The kagome superconductor CsV3Sb5 with exotic electronic properties has attracted substantial research interest, and the interplay between the superconductivity and the charge-density wave is crucial for understanding its unusual electronic ground state. In this work, we performed resistivity and AC magnetic susceptibility measurements on CsV3Sb5 single crystals uniaxially-strained along [100] and [110] directions. We find that the uniaxial-strain tuning effect of Tc (Tc/dε) and TCDW (dTCDW/dε) are almost identical along these distinct high-symmetry directions. These findings suggest the in-plane uniaxial-strain-tuning of Tc and TCDW in CsV3Sb5 are dominated by associated c-axis strain, whereas the response to purely in-plane strains is likely small.

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Improved RF power performance of InAlN/GaN HEMT by optimizing rapid thermal annealing process for high-performance low-voltage terminal applications Yuwei Zhou(周雨威), Minhan Mi(宓珉瀚), Pengfei Wang(王鹏飞), Can Gong(龚灿), Yilin Chen(陈怡霖), Zhihong Chen(陈治宏), Jielong Liu(刘捷龙), Mei Yang(杨眉), Meng Zhang(张濛), Qing Zhu(朱青), Xiaohua Ma(马晓华), and Yue Hao(郝跃) Chin. Phys. B, 2023, 32 (12):  127102.  DOI: 10.1088/1674-1056/acd8a1 Abstract ( 69 )   HTML ( 0 )   PDF (2757KB) ( 32 )   Improved radio-frequency (RF) power performance of InAlN/GaN high electron mobility transistor (HEMT) is achieved by optimizing the rapid thermal annealing (RTA) process for high-performance low-voltage terminal applications. By optimizing the RTA temperature and time, the optimal annealing condition is found to enable low parasitic resistance and thus a high-performance device. Besides, compared with the non-optimized RTA HEMT, the optimized one demonstrates smoother ohmic metal surface morphology and better heterojunction quality including the less degraded heterojunction sheet resistance and clearer heterojunction interfaces as well as negligible material out-diffusion from the barrier to the channel and buffer. Benefiting from the lowered parasitic resistance, improved maximum output current density of 2279 mA·mm-1 and higher peak extrinsic transconductance of 526 mS·mm-1 are obtained for the optimized RTA HEMT. In addition, due to the superior heterojunction quality, the optimized HEMT shows reduced off-state leakage current of 7×10-3 mA·mm-1 and suppressed current collapse of only 4%, compared with those of 1×10-1 mA·mm-1 and 15% for the non-optimized one. At 8 GHz and VDS of 6 V, a significantly improved power-added efficiency of 62% and output power density of 0.71 W·mm-1 are achieved for the optimized HEMT, as the result of the improvement in output current, knee voltage, off-state leakage current, and current collapse, which reveals the tremendous advantage of the optimized RTA HEMT in high-performance low-voltage terminal applications.

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Two-dimensional transition metal halide PdX2(X= F, Cl, Br, I): A promising candidate of bipolar magnetic semiconductors Miao-Miao Chen(陈苗苗), Sheng-Shi Li(李胜世), Wei-Xiao Ji(纪维霄), and Chang-Wen Zhang(张昌文) Chin. Phys. B, 2023, 32 (12):  127103.  DOI: 10.1088/1674-1056/ad04c3 Abstract ( 100 )   HTML ( 0 )   PDF (3743KB) ( 94 )   Two-dimensional (2D) nanomaterials with bipolar magnetism show great promise in spintronic applications. Manipulating carriers' spin-polarized orientation in bipolar magnetic semiconductor (BMS) requires a gate voltage, but that is volatile. Recently, a new method has been proposed to solve the problem of volatility by introducing a ferroelectric gate with proper band alignment. In this paper, we predict that the PdX2 (X = {F}, Cl, Br, I) monolayers are 2D ferromagnetic BMS with dynamic stability, thermal stability, and mechanical stability by first-principles calculations. The critical temperatures are higher than the boiling point of liquid nitrogen and the BMS characteristics are robust against external strains and electric fields for PdCl2 and PdBr2. Then, we manipulate the spin-polarization of PdCl2 and PdBr2 by introducing a ferroelectric gate to enable magnetic half-metal/semiconductor switching and spin-up/down polarization switching control. Two kinds of spin devices (multiferroic memory and spin filter) have been proposed to realize the spin-polarized directions of electrons. These results demonstrate that PdCl2 and PdBr2 with BMS characters can be widely used as a general material structure for spintronic devices.

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Tunable caging of excitation in decorated Lieb-ladder geometry with long-range connectivity Atanu Nandy Chin. Phys. B, 2023, 32 (12):  127201.  DOI: 10.1088/1674-1056/acf5ce Abstract ( 69 )   HTML ( 0 )   PDF (2817KB) ( 6 )   Controlled Aharonov-Bohm caging of wave train is reported in a quasi-one-dimensional version of Lieb geometry with next-nearest-neighbor hopping integral within the tight-binding framework. This longer-wavelength fluctuation is considered by incorporating periodic, quasi-periodic or fractal kind of geometry inside the skeleton of the original network. This invites exotic eigenspectrum displaying a distribution of flat band states. Also a subtle modulation of external magnetic flux leads to a comprehensive control over those non-resonant modes. Real space renormalization group method provides us an exact analytical prescription for the study of such tunable imprisonment of excitation. The non-trivial tunability of external agent is important as well as challenging in the context of experimental perspective.

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Mobility edges in one-dimensional finite-sized models with large quasi-periodic disorders Qiyun Tang(汤起芸) and Yan He(贺言) Chin. Phys. B, 2023, 32 (12):  127202.  DOI: 10.1088/1674-1056/accdc9 Abstract ( 86 )   HTML ( 0 )   PDF (15416KB) ( 30 )   We study the one-dimensional tight-binding model with quasi-periodic disorders, where the quasi-period is tuned to be large compared to the system size. It is found that this type of model with large quasi-periodic disorders can also support the mobility edges, which is very similar to the models with slowly varying quasi-periodic disorders. The energy-matching method is employed to determine the locations of mobility edges in both types of models. These results of mobility edges are verified by numerical calculations in various examples. We also provide qualitative arguments to support the fact that large quasi-periodic disorders will lead to the existence of mobility edges.

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Modulated optical and ferroelectric properties in a lateral structured ferroelectric/semiconductor van der Waals heterojunction Shanshan Chen(陈珊珊), Xinhao Zhang(张新昊), Guangcan Wang(王广灿), Shuo Chen(陈朔), Heqi Ma(马和奇), Tianyu Sun(孙天瑜), Baoyuan Man(满宝元), and Cheng Yang(杨诚) Chin. Phys. B, 2023, 32 (12):  127301.  DOI: 10.1088/1674-1056/acc7fa Abstract ( 98 )   HTML ( 0 )   PDF (2738KB) ( 24 )   Modulation between optical and ferroelectric properties was realized in a lateral structured ferroelectric CuInP2S6 (CIPS)/semiconductor MoS2 van der Waals heterojunction. The ferroelectric hysteresis loop area was modulated by the optical field. Two types of photodetection properties can be realized in a device by changing the ON and OFF states of the ferroelectric layer. The device was used as a photodetector in the OFF state but not in the ON state. The higher tunnelling electroresistance (~1.4×104) in a lateral structured ferroelectric tunnelling junction was crucial, and it was analyzed and modulated by the barrier height and width of the ferroelectric CIPS/semiconductor MoS2 Schottky junction. The new parameter of the ferroelectric hysteresis loop area as a function of light intensity was introduced to analyze the relationship between the ferroelectric and photodetection properties. The proposed device has potential application as an optoelectronic sensory cell in the biological nervous system or as a new type of photodetector.

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Real-time dynamics in strongly correlated quantum-dot systems Yong-Xi Cheng(程永喜), Zhen-Hua Li(李振华), Jian-Hua Wei(魏建华), and Hong-Gang Luo(罗洪刚) Chin. Phys. B, 2023, 32 (12):  127302.  DOI: 10.1088/1674-1056/acf448 Abstract ( 134 )   HTML ( 0 )   PDF (924KB) ( 93 )   We investigate the real-time dynamical properties of Rabi-type oscillation through strongly correlated quantum-dot systems by means of accurate hierarchical equations of motion. It is an extension of the hierarchical Liouville-space approach for addressing strongly correlated quantum-dot systems. We study two paradigmatic models, the single quantum-dot system, and serial coupling double quantum-dot system. We calculate accurately the time-dependent occupancy of quantum-dot systems subject to a sudden change of gate voltage. The Rabi-type oscillation of the occupancy and distinct relaxation time of the quantum-dot systems with different factors are described. This is helpful to understand dissipation and decoherence in real-time dynamics through nanodevices and provides a theoretical frame to experimental investigation and manipulation of molecular electronic devices.

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Magnetic and magnetotransport properties of layered TaCoTe2 single crystals Ming Mei(梅明), Zheng Chen(陈正), Yong Nie(聂勇), Yuanyuan Wang(王园园), Xiangde Zhu(朱相德), Wei Ning(宁伟), and Mingliang Tian(田明亮) Chin. Phys. B, 2023, 32 (12):  127303.  DOI: 10.1088/1674-1056/acd10a Abstract ( 115 )   HTML ( 0 )   PDF (754KB) ( 62 )   We present the synthesis of TaCoTe2 single crystals and a systematic investigation of the physical properties of bulk crystals and thin flakes. The crystal shows a semiconducting behavior with temperature decreasing from room temperature and turns to a metallic behavior below 38 K. When the magnetic field is applied, the temperature-dependent resistivity curves show an upturn below 10 K. Furthermore, we find that the TaCoTe2 single crystal can be easily exfoliated from the bulk crystal by the micromechanical exfoliation method. Our measurements suggest that the nanoflakes have properties similar to those of the bulk crystal when the thickness is lowered to 18 nm.

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Role of grain boundary networks in vortex motion in superconducting films Yu Liu(刘宇), Feng Xue(薛峰), and Xiao-Fan Gou(苟晓凡) Chin. Phys. B, 2023, 32 (12):  127401.  DOI: 10.1088/1674-1056/ace315 Abstract ( 83 )   HTML ( 0 )   PDF (1361KB) ( 12 )   We study the vortex dynamics of the polycrystalline superconductors in the presence of both random point defects and the generated grain boundary (GB) networks with Voronoi diagram. The synergistic effect of adjacent GBs on restricting the vortex motion in intragranular region is proposed and the corresponding intensity factor of the synergistic effect which characterizes the strength of the synergistic restriction of adjacent grain boundaries is also determined in the present work. The interconnected GBs offer easy-flow channels for vortices in addition to pinning effects on the vortices. The combined channels and the vortex flow patterns in the superconducting film are analyzed in detail from molecular dynamics simulations. Furthermore, it is discovered that the critical current increases with the decrease of magnetic field intensity, temperature, and the average grain size. The large number of vortices results in the enhanced repulsive interaction forcing the vortices to move out from the GBs. The thermal depinning from GBs leads to the lower Lorentz force range. The increase of the grain size causes the number of GBs to decrease. In summary, these effects leads the critical current to become a decreasing function of magnetic field, temperature, and grain size.

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Effects of irradiation on superconducting properties of small-grained MgB2 thin films Li Liu(刘丽), Jung Min Lee, Yoonseok Han, Jaegu Song, Chorong Kim, Jaekwon Suk, Won Nam Kang, Jie Liu(刘杰), Soon-Gil Jung, and Tuson Park Chin. Phys. B, 2023, 32 (12):  127402.  DOI: 10.1088/1674-1056/acf5d3 Abstract ( 95 )   HTML ( 0 )   PDF (1502KB) ( 43 )   We investigate the effect of ion irradiation on MgB2 thin films with small grains of approximately 122 nm and 140 nm. The flux pinning by grain boundaries is insignificant in the pristine MgB2 films due to good inter-grain connectivity, but is significantly improved after 120-keV Mn-ion irradiation. The scaling behavior of the flux pinning force density for the ion-irradiated MgB2 thin films with nanoscale grains demonstrates the predominance of pinning by grain boundaries, in contrast to the single-crystalline MgB2 films where normal point pinning was dominant after low-energy ion irradiation. These results suggest that irradiation-induced defects can accumulate near the grain boundaries in metallic MgB2 superconductors.

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Effect of spin-reorientation transition of cell boundary phases on the temperature dependence of magnetization and coercivity in Sm2Co17 magnets Si-Si Tu(涂思思), Lei Liu(刘雷), Bo Zhou(周波), Chuang-Hui Dong(董创辉), Li-Ming Ye(叶力铭), Ying-Li Sun(孙颖莉), Yong Ding(丁勇), A-Ru Yan(闫阿儒), and Xin-Biao Mao(毛信表) Chin. Phys. B, 2023, 32 (12):  127501.  DOI: 10.1088/1674-1056/acc80b Abstract ( 92 )   HTML ( 0 )   PDF (4789KB) ( 35 )   Four Sm2Co17 magnets with spin-reorientation transition (SRT) of cell boundary phases (CBPs) are prepared by liquid-phase sintering. The temperature of the SRT of CBPs (TSR1:5) is regulated from 125 K to 195 K by adding 0 wt.%, 3 wt.%, 6 wt.% and 9 wt.% Dy88Cu12 alloy powder. The effect of SRT of Sm2Co17 magnet CBPs on the temperature dependence of the magnetization (M-T) and coercivity (H-T) is systematically investigated. The temperature dependence of the magnetization is influenced by the SRT of CBPs. The M-T curves measured during the heating process are larger than those measured during the cooling process when T < TSR1:5. When T = TSR1:5 there is a bifurcation point. When T>TSR1:5 the M-T curves overlap and the M-T derivation curve shows that the magnetization of the magnet has low temperature dependence of magnetization above TSR1:5. With increasing TSR1:5, the initial temperature of the low temperature dependence of magnetization shifts towards a higher temperature. The coercivity temperature coefficient becomes positive as the SRT effect increases, and the temperature range of the positive coercivity temperature coefficient moves towards higher temperatures as TSR1:5 increases. This reveals that SRT of CBPs has little effect on the temperature dependence of magnetization above TSR1:5, while the temperature dependence of coercivity is optimized. The temperature range of magnetization and coercivity with low temperature dependence tends towards higher temperatures, which is conducive to the preparation of magnets with a low temperature coefficient at higher temperatures.

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Observation of spin-glass behavior in 1111-type magnetic semiconductor (La, Ba)(Zn, Mn)SbO Xueqin Zhao(赵雪芹), Jinou Dong(董金瓯), Rufei Zhang(张茹菲), Qiaolin Yang(杨巧林), Lingfeng Xie(谢玲凤), Licheng Fu(傅立承), Yilun Gu(顾轶伦), Xun Pan(潘洵), and Fanlong Ning(宁凡龙) Chin. Phys. B, 2023, 32 (12):  127502.  DOI: 10.1088/1674-1056/acf44a Abstract ( 80 )   HTML ( 0 )   PDF (1712KB) ( 39 )   We report the successful fabrication of a new 1111-type bulk magnetic semiconductor (La,Ba)(Zn,Mn)SbO through the solid solution of (La,Ba) and (Zn,Mn) in the parent compound LaZnSbO. The polycrystalline samples (La,Ba)(Zn,Mn)SbO crystallize into ZrCuSiAs-type tetragonal structure, which has the same structure as iron-based superconductor LaFeAsO1-δ. The DC magnetization measurements indicate the existence of spin-glass ordering, and the coercive field is up to ~ 11500 Oe (1 Oe=79.5775 A·m-1). The AC magnetic susceptibility further determines that the samples evolve into a conventional spin-glass ordering state below the spin freezing temperature Tf. In addition, the negative magnetoresistance (MR ≡[ρ(H)-ρ(0)]/ρ(0)) reaches - 88% under 9 T.

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Effect of seed layers on the static and dynamic magnetic properties of CoIr films with negative effective magnetocrystalline anisotropy Tianyong Ma(马天勇), Sha Zhang(张莎), Chenhu Zhang(张晨虎), Zhiwei Li(李志伟), Tao Wang(王涛), and Fashen Li(李发伸) Chin. Phys. B, 2023, 32 (12):  127503.  DOI: 10.1088/1674-1056/acd523 Abstract ( 73 )   HTML ( 0 )   PDF (2046KB) ( 13 )   The c-axis oriented hcp-Co81Ir19 magnetic films were prepared on different seed layers (Ni, Cu, Ir, Pt, Au, and No seed). We systematically investigated the impact that surface-free energy and strain energy have on the orientation and defects and/or internal stress of the grains by increasing the lattice mismatch ratio. Moreover, the initial permeability and the natural resonance frequency were discussed in great detail using a comparison between calculated values and experimental values. We found that the almost unchanged 4πMs and μi are not affected, while the changed Hc, intrinsic Kgrain, and fr are strongly dependent on the seed layer and seed layer material. Moreover, the extracted damping constant is sensitive to the defects and/or internal stress and orientation of the grains. Therefore, the soft magnetic properties and microwave properties are adjusted and optimized by seed layers with different materials.

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Room-temperature creation and manipulation of skyrmions in MgO/FeNiB/Mo multilayers Hot! Wen-Hui Liang(梁文会), Jian Su(苏鉴), Yu-Tong Wang(王雨桐), Ying Zhang(张颖), Feng-Xia Hu(胡凤霞), and Jian-Wang Cai(蔡建旺) Chin. Phys. B, 2023, 32 (12):  127504.  DOI: 10.1088/1674-1056/acf5d4 Abstract ( 412 )   HTML ( 0 )   PDF (6693KB) ( 492 )   Magnetic skyrmions in multilayer structures are considered as a new direction for the next generation of storage due to their small size, strong anti-interference ability, high current-driven mobility, and compatibility with existing spintronic technology. In this work, we present a tunable room temperature skyrmion platform based on multilayer stacks of MgO/FeNiB/Mo. We systematically studied the creation of magnetic skyrmions in MgO/FeNiB/Mo multilayer structures with perpendicular magnetic anisotropy (PMA). In these structures, the magnetic anisotropy changes from PMA to in-plane magnetic anisotropy (IMA) as the thickness of FeNiB layer increases. By adjusting the applied magnetic field and electric current, stable and high-density skyrmions can be obtained in the material system. The discovery of this material broadens the exploration of new materials for skyrmion and promotes the development of spintronic devices based on skyrmions.

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Periodical polarization reversal modulation in multiferroic MnWO4 under high magnetic fields Congbin Liu(刘从斌), Jinbing Cheng(程晋炳), Junbao He(何俊宝), Yongsheng Zhu(朱永胜), Wan Chang(常婉), Xiaoyu Lu(路晓宇), Junfeng Wang(王俊峰), Meiyan Cui(崔美艳), Jinshu Huang(黄金书), Dawei Zhou(周大伟), Rui Chen(陈瑞), Hao Jiang(江浩),Chuangchuang Ma(马创创), Chao Dong(董超), and Yongsong Luo(罗永松) Chin. Phys. B, 2023, 32 (12):  127505.  DOI: 10.1088/1674-1056/acca07 Abstract ( 85 )   HTML ( 0 )   PDF (7830KB) ( 22 )   We report polarization reversal periodically controlled by the electric field in multiferroic MnWO4 with a pulsed field up to 52 T. The electric polarization cannot be reversed by successive opposite electric fields in low magnetic fields (< 14 T) at 4.2 K, whereas polarization reversal is directly achieved by two opposite electric fields under high magnetic fields (< 45 T). Interestingly, the polarization curve of rising and falling fields for H||u (magnetic easy axis) is irreversible when the magnetic field is close to 52 T. In this case, the rising and falling polarization curves can be individually reversed by the electric field, and thus require five cycles to recover to the initial condition by the order of the applied electric fields (+E, -E, -E, +E, +E). In addition, we find that ferroelectric phase IV can be tuned from parallel to antiparallel in relation to ferroelectric phase AF2 by applying a magnetic field approximated to the c axis.

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Inertial effect on minimum magnetic field for magnetization reversal in ultrafast magnetism Xue-Meng Nan(南雪萌), Chuan Qu(屈川), Peng-Bin He(贺鹏斌), and Zai-Dong Li(李再东) Chin. Phys. B, 2023, 32 (12):  127506.  DOI: 10.1088/1674-1056/acd3de Abstract ( 97 )   HTML ( 0 )   PDF (650KB) ( 13 )   In the field of ultrafast magnetism, i.e., subpicosecond or femtosecond time scales, the dynamics of magnetization can be described by the inertial Landau-Lifhitz-Gilbert equation. In terms of this equation, the intrinsic characteristics are investigated in detail for the theoretical limit of the magnetization reversal field. We can find that there is a critical value for the inertia parameter τc, which is affected by the damping and anisotropy parameter of the system. When the inertial parameter factor τ<τc, the limit value of the magnetization reversal field under the ultrafast magnetic mechanism is smaller than that of the fast magnetic mechanism. When τ>τc, the limit value of the magnetization reversal field will be larger than the limit value under the fast magnetic mechanism. Moreover, it is important to point out that the limit value of the magnetization reversal field under the ultrafast magnetic mechanism decreases with the increasing inertial factor, as τ<τc/2, which increases with inertial factor τ as τ>τc/2. Finally, with the joint action of damping and anisotropy, compared with fast magnetism, we find that the limit value of the magnetization reversal field has rich variation characteristics, i.e., there is not only a linear and proportional relationship, but also an inverse relationship, which is very significant for the study of ultrafast magnetism.

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Analysis on the cation distribution of MgxNi1-xFe2O4(x=0, 0.25, 0.5, 0.75, 1) using Mössbauer spectroscopy and magnetic measurement Shiyu Xu(徐诗语), Jiajun Mo(莫家俊), Lebin Liu(刘乐彬), and Min Liu(刘 敏) Chin. Phys. B, 2023, 32 (12):  127507.  DOI: 10.1088/1674-1056/acca0c Abstract ( 74 )   HTML ( 0 )   PDF (1332KB) ( 8 )   MgxNi1-xFe2O4 (x=0, 0.25, 0.5, 0.75, 1) spinel ferrite material was analyzed to determine its magnetic properties and structure. X-ray diffraction (XRD), Mössbauer spectroscopy, and vibrating sample magnetometer (VSM) characterization were performed on the samples prepared using the sol-gel method. The results from XRD confirmed the existence of the single-phase cubic spinel structures Fd$\mathop 3\limits^ -$m, as well as the evolution of the crystalline size (D), the lattice parameter (a) and cell volume in compounds. The Mössbauer spectra showed the distribution of cations and changes in the magnetic properties of the sample. VSM measurement revealed that the samples were room-temperature ferromagnetic. Moreover, the saturation magnetization (Ms) of the samples changed with the Mg2+ ion content x, and a maximum occured at x = 0.5. Doping with Mg2+ ions increased the transfer of Ni2+ ions to tetrahedral sites, thus increasing the magnetic moment difference between tetrahedral (A) and octahedral (B) sites. Specifically, doping NiFe2O4 with Mg2+ ions can enhance its magnetic properties and enhance its saturation magnetization.

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Multi-segmented nanowires for vortex magnetic domain wall racetrack memory M Al Bahri, M Al Hinaai, and T Al Harthy Chin. Phys. B, 2023, 32 (12):  127508.  DOI: 10.1088/1674-1056/acca0a Abstract ( 63 )   HTML ( 0 )   PDF (2219KB) ( 27 )   A vortex domain wall's (VW) magnetic racetrack memory's high performance depends on VW structural stability, high speed, low power consumption and high storage density. In this study, these critical parameters were investigated in magnetic multi-segmented nanowires using micromagnetic simulation. Thus, an offset magnetic nanowire with a junction at the center was proposed for this purpose. This junction was implemented by shifting one portion of the magnetic nanowire horizontally in the x-direction (l) and vertically (d) in the y-direction. The VW structure became stable by manipulating magnetic properties, such as magnetic saturation (Ms) and magnetic anisotropy energy (Ku). In this case, increasing the values of Ms≥ 800 kA/m keeps the VW structure stable during its dynamics and pinning and depinning in offset nanowires, which contributes to maintenance of the storage memory's lifetime for a longer period. It was also found that the VW moved with a speed of 500 m/s, which is desirable for VW racetrack memory devices. Moreover, it was revealed that the VW velocity could be controlled by adjusting the offset area dimensions (l and d), which helps to drive the VW by using low current densities and reducing the thermal-magnetic spin fluctuations. Further, the depinning current density of the VW (Jd) over the offset area increases as d increases and l decreases. In addition, magnetic properties, such as the Ms and Ku, can affect the depinning process of the VW through the offset area. For high storage density, magnetic nanowires (multi-segmented) with four junctions were designed. In total, six states were found with high VW stability, which means three bits per cell. Herein, we observed that the depinning current density (Jd) for moving the VW from one state to another was highly influenced by the offset area geometry (l and d) and the material's magnetic properties, such as the Ms and Ku.

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Discovery of new potential magnetic semiconductors in quaternary Heusler compounds by addition of lanthanides Jin Guo(郭金), Shiyi Feng(冯时怡), Rong Tao(陶容), Guoxia Wang(王国霞), Yue Wang(王越), and Zhifeng Liu(刘志锋) Chin. Phys. B, 2023, 32 (12):  127509.  DOI: 10.1088/1674-1056/acfaf7 Abstract ( 103 )   HTML ( 0 )   PDF (942KB) ( 41 )   Magnetic semiconductors have attracted a lot of attention by having both electronic charge and spin degrees of freedom. In this paper, we obtained twenty magnetic semiconductors such as FeVLaSb, FeVPrSb, FeCrTbSi, CoVDySi, and CoVHoSi by adding lanthanides to quaternary Heusler compounds based on the Slater-Pauling law and orbital hybridization theory. The relationship between the lattice constants and energy gaps of the magnetic semiconductors with lanthanide elements is investigated by in-depth analysis. These magnetic semiconductors of quaternary Heusler compounds are promising candidates to find applications as spin filtering materials in spintronics devices.

INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY

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Molecular dynamics study of thermal conductivities of cubic diamond, lonsdaleite, and nanotwinned diamond via machine-learned potential Jia-Hao Xiong(熊佳豪), Zi-Jun Qi(戚梓俊), Kang Liang(梁康), Xiang Sun(孙祥), Zhan-Peng Sun(孙展鹏), Qi-Jun Wang(汪启军), Li-Wei Chen(陈黎玮), Gai Wu(吴改), and Wei Shen(沈威) Chin. Phys. B, 2023, 32 (12):  128101.  DOI: 10.1088/1674-1056/ace4b4 Abstract ( 103 )   HTML ( 0 )   PDF (2931KB) ( 60 )   Diamond is a wide-bandgap semiconductor with a variety of crystal configurations, and has the potential applications in the field of high-frequency, radiation-hardened, and high-power devices. There are several important polytypes of diamonds, such as cubic diamond, lonsdaleite, and nanotwinned diamond (NTD). The thermal conductivities of semiconductors in high-power devices at different temperatures should be calculated. However, there has been no reports about thermal conductivities of cubic diamond and its polytypes both efficiently and accurately based on molecular dynamics (MD). Here, using interatomic potential of neural networks can provide obvious advantages. For example, comparing with the use of density functional theory (DFT), the calculation time is reduced, while maintaining high accuracy in predicting the thermal conductivities of the above-mentioned three diamond polytypes. Based on the neuroevolution potential (NEP), the thermal conductivities of cubic diamond, lonsdaleite, and NTD at 300 K are respectively 2507.3 W·m-1·K-1, 1557.2 W·m-1·K-1, and 985.6 W·m-1·K-1, which are higher than the calculation results based on Tersoff-1989 potential (1508 W·m-1·K-1, 1178 W·m-1·K-1, and 794 W·m-1·K-1, respectively). The thermal conductivities of cubic diamond and lonsdaleite, obtained by using the NEP, are closer to the experimental data or DFT data than those from Tersoff-potential. The molecular dynamics simulations are performed by using NEP to calculate the phonon dispersions, in order to explain the possible reasons for discrepancies among the cubic diamond, lonsdaleite, and NTD. In this work, we propose a scheme to predict the thermal conductivity of cubic diamond, lonsdaleite, and NTD precisely and efficiently, and explain the differences in thermal conductivity among cubic diamond, lonsdaleite, and NTD.

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Diamond growth in a high temperature and high pressure Fe-Ni-C-Si system: Effect of synthesis pressure Yang Liu(刘杨), Zhiwen Wang(王志文), Bowei Li(李博维), Hongyu Zhao(赵洪宇), Shengxue Wang(王胜学), Liangchao Chen(陈良超), Hongan Ma(马红安), and Xiaopeng Jia(贾晓鹏) Chin. Phys. B, 2023, 32 (12):  128102.  DOI: 10.1088/1674-1056/acf03d Abstract ( 97 )   HTML ( 0 )   PDF (1449KB) ( 75 )   Pressure is one of the necessary conditions for diamond growth. Exploring the influence of pressure on growth changes in silicon-doped diamonds is of great value for the production of high-quality diamonds. This work reports the morphology, impurity content and crystal quality characteristics of silicon-doped diamond crystals synthesized under different pressures. Fourier transform infrared spectroscopy shows that with the increase of pressure, the nitrogen content in the C- center inside the diamond crystal decreases. X-ray photoelectron spectroscopy test results show the presence of silicon in the diamond crystals synthesized by adding silicon powder. Raman spectroscopy data shows that the increase in pressure in the Fe-Ni-C-Si system shifts the Raman peak of diamonds from 1331.18 cm-1 to 1331.25 cm-1, resulting in a decrease in internal stress in the crystal. The half-peak width decreased from 5.41 cm-1 to 5.26 cm-1, and the crystallinity of the silicon-doped diamond crystals improved, resulting in improved quality. This work provides valuable data that can provide a reference for the synthesis of high-quality silicon-doped diamonds.

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Transient study of droplet oscillation characteristics driven by an electric field Yan-Fei Gao(高燕飞), Wei-Feng He(何纬峰), Adam Abdalazeem, Qi-Le Shi(施其乐), Ji-Rong Zhang(张继荣),Peng-Fei Su(苏鹏飞), Si-Yong Yu(俞思涌), Zhao-Hui Yao(姚照辉), and Dong Han(韩东) Chin. Phys. B, 2023, 32 (12):  128201.  DOI: 10.1088/1674-1056/accd47 Abstract ( 99 )   HTML ( 0 )   PDF (2743KB) ( 15 )   Electrowetting technology, a microfluidic technology, has attracted more and more attention in recent years and has broad prospects in terms of microdroplet drive. In this paper, the dynamic contact angle theory is used to develop a numerical model to predict the droplet dynamic contact behavior and internal flow field under electrowetting. In particular, based on the established computational model of droplet force balance, the dynamic process of a droplet under electrowetting is analyzed, including the perspective of pressure variation and force balance inside the droplet. The results show that when the alternating current frequency increases from 50 Hz to 500 Hz, the amplitude of the oscillation waveform after droplet stabilization is 0.036 mm, 0.016 mm, 0.013 mm and 0.002 mm, while the relevant droplet oscillation period T is 11 ms, 4 ms, 2 ms and 1 ms, respectively. It is also found that the initial phase angle does not affect the droplet oscillation amplitude. In addition, the pressure on the droplet surface under alternating current electrowetting increases rapidly to the maximum value with resonant waveform oscillation, and the droplet will present different resonance modes under voltage stimulation. The higher the resonance mode is, the smaller the droplet oscillation amplitude is and the streamline at the interface will present an eddy current, in which the number of vortices matches the resonance mode. A high resonance mode corresponds to a small droplet amplitude, while there are more vortices with a smaller size.

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Degradation mechanism of high-voltage single-crystal LiNi0.5Co0.2Mn0.3O2 cathode material Na Liu(柳娜) Chin. Phys. B, 2023, 32 (12):  128202.  DOI: 10.1088/1674-1056/ad01a3 Abstract ( 92 )   HTML ( 0 )   PDF (4305KB) ( 72 )   Layered cathode materials have been successfully commercialized and applied to electric vehicles. To further improve improve the energy density of these marterials is still the main efforts in the market. Therefore, developing high-voltage LiNixCoyMnzO2 (x+y+z=1, NCM) to achieve high energy density is particularly important. However, under high voltage cycling, NCM often exhibits rapid capacity degradation, which can be attributed to oxygen release, structural phase transition and particle cracking. In this work, the representative single-crystal LiNi0.5Co0.2Mn0.3O2 (NCM523) was studied under various high charge cut-off voltages. Analysis by x-ray diffraction (XRD), transmission electron microscope (TEM) and electron back scatter diffraction (EBSD) measurements indicated that the rock-salt phase is formed on the surface of the particles after high voltage cycling, which is responsible for the increase of impedance and the rapid decay of capacity. Therefore, inhibiting the formation of rock-salt phase is believed an effective strategy to address the failure of NCM under high voltages. These findings provide effective guidance for the development of high-voltage NCM.

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Single-flux-quantum-based qubit control with tunable driving strength Kuang Liu(刘匡), Yifan Wang(王一凡), Bo Ji(季波), Wanpeng Gao(高万鹏), Zhirong Lin(林志荣), and Zhen Wang(王镇) Chin. Phys. B, 2023, 32 (12):  128501.  DOI: 10.1088/1674-1056/acf5d0 Abstract ( 118 )   HTML ( 0 )   PDF (806KB) ( 62 )   Single-flux-quantum (SFQ) circuits have great potential in building cryogenic quantum-classical interfaces for scaling up superconducting quantum processors. SFQ-based quantum gates have been designed and realized. However, current control schemes are difficult to tune the driving strength to qubits, which restricts the gate length and usually induces leakage to unwanted levels. In this study, we design the scheme and corresponding pulse generator circuit to continuously adjust the driving strength by coupling SFQ pulses with variable intervals. This scheme not only provides a way to adjust the SFQ-based gate length, but also proposes the possibility to tune the driving strength envelope. Simulations show that our scheme can suppress leakage to unwanted levels and reduce the error of SFQ-based Clifford gates by more than an order of magnitude.

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Investigation of degradation and recovery characteristics of NBTI in 28-nm high-k metal gate process Wei-Tai Gong(巩伟泰), Yan Li(李闫), Ya-Bin Sun(孙亚宾), Yan-Ling Shi(石艳玲), and Xiao-Jin Li(李小进) Chin. Phys. B, 2023, 32 (12):  128502.  DOI: 10.1088/1674-1056/ace034 Abstract ( 96 )   HTML ( 0 )   PDF (823KB) ( 26 )   Degradation induced by the negative bias temperature instability (NBTI) can be attributed to three mutually uncoupled physical mechanisms, i.e., the generation of interface traps (Δ VIT), hole trapping in pre-existing gate oxide defects (Δ VHT), and the generation of gate oxide defects (Δ VOT). In this work, the characteristic of NBTI for p-type MOSFET fabricated by using a 28-nm high-k metal gate (HKMG) process is thoroughly studied. The experimental results show that the degradation is enhanced at a larger stress bias and higher temperature. The effects of the three underlying subcomponents are evaluated by using the comprehensive models. It is found that the generation of interface traps dominates the NBTI degradation during long-time NBTI stress. Moreover, the NBTI parameters of the power-law time exponent and temperature activation energy as well as the gate oxide field acceleration are extracted. The dependence of operating lifetime on stress bias and temperature is also discussed. It is observed that NBTI lifetime significantly decreases as the stress increases. Furthermore, the decrease of charges related to interface traps and hole detrapping in pre-existing gate oxide defects are used to explain the recovery mechanism after stress.

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Improving dynamic characteristics for IGBTs by using interleaved trench gate Yi-Fan Wu(吴毅帆), Gao-Qiang Deng(邓高强), Chen Tan(谭琛), Shi-Wei Liang(梁世维), and Jun Wang(王俊) Chin. Phys. B, 2023, 32 (12):  128503.  DOI: 10.1088/1674-1056/ace15d Abstract ( 102 )   HTML ( 0 )   PDF (1607KB) ( 30 )   A novel trench insulated gate bipolar transistor (IGBT) with improved dynamic characteristics is proposed and investigated. The poly gate and poly emitter of the proposed IGBT are arranged alternately along the trench. A self-biased p-MOSFET is formed on the emitter side. Owing to this unique three-dimensional (3D) trench architecture, both the turn-off characteristic and the turn-on characteristic can be greatly improved. At the turn-off moment, the maximum electric field and impact ionization rate of the proposed IGBT decrease and the dynamic avalanche (DA) is suppressed. Comparing with the carrier-stored trench gate bipolar transistor (CSTBT), the turn-off loss (Eoff) of the proposed IGBT also decreases by 31% at the same ON-state voltage. At the turn-on moment, the built-in p-MOSFET reduces the reverse displacement current (IG_dis), which is conducive to lowing dIC/dt. As a result, compared with the CSTBT with the same turn-on loss (Eon), at IC = 20 A/cm2, the proposed IGBT decreases by 35% of collector surge current (Isurge) and 52% of d IC/dt.

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Si-Ge based vertical tunnel field-effect transistor of junction-less structure with improved sensitivity using dielectric modulation for biosensing applications Lucky Agarwal, Varun Mishra, Ravi Prakash Dwivedi, Vishal Goyal, and Shweta Tripathi Chin. Phys. B, 2023, 32 (12):  128701.  DOI: 10.1088/1674-1056/acc7f6 Abstract ( 82 )   HTML ( 0 )   PDF (1231KB) ( 7 )   A dielectric modulation strategy for gate oxide material that enhances the sensing performance of biosensors in junction-less vertical tunnel field effect transistors (TFETs) is reported. The junction-less technique, in which metals with specific work functions are deposited on the source region to modulate the channel conductivity, is used to provide the necessary doping for the proper functioning of the device. TCAD simulation studies of the proposed structure and junction structure have been compared, and showed an enhanced rectification of 104 times. The proposed structure is designed to have a nanocavity of length 10 nm on the left- and right-hand sides of the fixed gate dielectric, which improves the biosensor capture area, and hence the sensitivity. By considering neutral and charged biomolecules with different dielectric constants, TCAD simulation studies were compared for their sensitivities. The off-state current IOFF can be used as a suitable sensing parameter because it has been observed that the proposed sensor exhibits a significant variation in drain current. Additionally, it has been investigated how positively and negatively charged biomolecules affect the drain current and threshold voltage. To explore the device performance when the nanogaps are fully filled, half filled and unevenly filled, extensive TCAD simulations have been run. The proposed TFET structure is further benchmarked to other structures to show its better sensing capabilities.

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Resolution-enhanced single-pixel imaging using the Hadamard transform matrix Shu-Hang Bie(别书航), Chen-Hui Wang(王晨晖), Rui-Bing Lv(吕瑞兵), Qian-Qian Bao(鲍倩倩),Qiang Fu(付强), Shao-Ying Meng(孟少英), and Xi-Hao Chen(陈希浩) Chin. Phys. B, 2023, 32 (12):  128702.  DOI: 10.1088/1674-1056/accf7d Abstract ( 92 )   HTML ( 0 )   PDF (607KB) ( 30 )   We propose a single-pixel imaging (SPI) method to achieve a higher-resolution image via the Hadamard transform matrix. Unlike traditional SPI schemes, this new method recovers images by correlating single-pixel signals with synchronized transformed patterns of Hadamard bases that are actually projected onto the digital micromirror device. Each transform pattern is obtained through the inverse Fourier transform of the pattern acquired by Gaussian filtering of each Hadamard basis in the frequency domain. The proposed scheme is based on a typical SPI experimental setup and does not add any hardware complexity, enabling the transformation of Hadamard matrices and image reconstruction through data processing alone. Therefore, this approach could be considered as an alternative option for achieving fast SPI in a diffraction-limited imaging system, without the need for additional hardware.

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Unraveling the molecular mechanism of prion disease: Insights from α2 area mutations in human prion protein Rongri Tan(谈荣日), Kui Xia(夏奎), Damao Xun(寻大毛), Wenjun Zong(宗文军), and Yousheng Yu(余幼胜) Chin. Phys. B, 2023, 32 (12):  128703.  DOI: 10.1088/1674-1056/ad08a8 Abstract ( 90 )   HTML ( 0 )   PDF (1437KB) ( 79 )   Prion diseases are a class of fatal neurodegenerative diseases caused by misfolded prion proteins. The main reason is that pathogenic prion protein has a strong tendency to aggregate, which easily induces the damage to the central nervous system. Point mutations in the human prion protein gene can cause prion diseases such as Creutzfeldt-Jakob and Gerstmann's syndrome. To understand the mechanism of mutation-induced prion protein aggregation, the mutants in an aqueous solution are studied by molecular dynamics simulations, including the wild type, V180I, H187R and a double point mutation which is associated with CJD and GSS. After running simulations for 500 ns, the results show that these three mutations have different effects on the kinetic properties of PrP. The high fluctuations around the N-terminal residues of helix 2 in the V180I variant lead to a decrease in hydrogen bonding on helix 2, while an increase in the number of hydrogen bonds between the folded regions promotes the generation of β-sheet. Meanwhile, partial deletion of salt bridges in the H187R and double mutants allows the sub-structural domains of the prion protein to separate, which would accelerate the conversion from PrPC to PrPSc. A similar trend is observed in both SASA and Rg for all three mutations, indicating that the conformational space is reduced and the structure is compact.

CORRIGENDUM

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Corrigendum to “Electromagnetically induced transparency via localized surface plasmon mode-assisted hybrid cavity QED” Xiaomiao Li(李晓苗), Famin Liu(刘发民), Zigeng Li(李子更), Hongyan Zhu(朱虹燕), Fan Wang(王帆), and Xiaolan Zhong(钟晓岚) Chin. Phys. B, 2023, 32 (12):  129901.  DOI: 10.1088/1674-1056/ad0bf7 Abstract ( 77 )   HTML ( 0 )   PDF (920KB) ( 12 )   We would like to point out the misprinted Fig. 3 in our published paper [Chin. Phys. B 32, 114205 (2023)]. Since only orders of subfigures need to be corrected and the main results of the published paper are correct, we present the correct figure in this corrigendum.