Table of contents

15 August 2024, Volume 33 Issue 8 Previous issue    Next issue

• Download table of contents
• Download cover

TOPICAL REVIEW — Stephen J. Pennycook: A research life in atomic-resolution STEM and EELS

Select

Three-dimensional crystal defect imaging by STEM depth sectioning Ryo Ishikawa, Naoya Shibata, and Yuichi Ikuhara Chin. Phys. B, 2024, 33 (8):  086101.  DOI: 10.1088/1674-1056/ad4ff9 Abstract ( 189 )   HTML ( 6 )   PDF (3402KB) ( 282 )   One of the major innovations awaiting in electron microscopy is full three-dimensional imaging at atomic resolution. Despite the success of aberration correction to deep sub-ångström lateral resolution, spatial resolution in depth is still far from atomic resolution. In scanning transmission electron microscopy (STEM), this poor depth resolution is due to the limitation of the illumination angle. To overcome this physical limitation, it is essential to implement a next-generation aberration corrector in STEM that can significantly improve the depth resolution. This review discusses the capability of depth sectioning for three-dimensional imaging combined with large-angle illumination STEM. Furthermore, the statistical analysis approach remarkably improves the depth resolution, making it possible to achieve three-dimensional atomic resolution imaging at oxide surfaces. We will also discuss the future prospects of three-dimensional imaging at atomic resolution by STEM depth sectioning.

Select

Cryogenic transmission electron microscopy on beam-sensitive materials and quantum science Gang Wang(王刚) and Jun-Hao Lin(林君浩) Chin. Phys. B, 2024, 33 (8):  086801.  DOI: 10.1088/1674-1056/ad5af0 Abstract ( 155 )   HTML ( 8 )   PDF (1379KB) ( 239 )   Transmission electron microscopy (TEM) offers unparalleled atomic-resolution imaging of complex materials and heterogeneous structures. However, high-energy imaging electrons can induce structural damage, posing a challenge for electron-beam-sensitive materials. Cryogenic TEM (Cryo-TEM) has revolutionized structural biology, enabling the visualization of biomolecules in their near-native states at unprecedented detail. The low electron dose imaging and stable cryogenic environment in Cryo-TEM are now being harnessed for the investigation of electron-beam-sensitive materials and low-temperature quantum phenomena. Here, we present a systematic review of the interaction mechanisms between imaging electrons and atomic structures, illustrating the electron beam-induced damage and the mitigating role of Cryo-TEM. This review then explores the advancements in low-dose Cryo-TEM imaging for elucidating the structures of organic-based materials. Furthermore, we showcase the application of Cryo-TEM in the study of strongly correlated quantum materials, including the detection of charge order and novel topological spin textures. Finally, we discuss the future prospects of Cryo-TEM, emphasizing its transformative potential in unraveling the complexities of materials and phenomena across diverse scientific disciplines.

SPECIAL TOPIC — Stephen J. Pennycook: A research life in atomic-resolution STEM and EELS

Select

Controlled fabrication of freestanding monolayer SiC by electron irradiation Yunli Da(笪蕴力), Ruichun Luo(罗瑞春), Bao Lei(雷宝), Wei Ji(季威), and Wu Zhou(周武) Chin. Phys. B, 2024, 33 (8):  086802.  DOI: 10.1088/1674-1056/ad6132 Abstract ( 168 )   HTML ( 4 )   PDF (1273KB) ( 148 )   The design and preparation of novel quantum materials with atomic precision are crucial for exploring new physics and for device applications. Electron irradiation has been demonstrated as an effective method for preparing novel quantum materials and quantum structures that could be challenging to obtain otherwise. It features the advantages of precise control over the patterning of such new materials and their integration with other materials with different functionalities. Here, we present a new strategy for fabricating freestanding monolayer SiC within nanopores of a graphene membrane. By regulating the energy of the incident electron beam and the in-situ heating temperature in a scanning transmission electron microscope (STEM), we can effectively control the patterning of nanopores and subsequent growth of monolayer SiC within the graphene lattice. The resultant SiC monolayers seamlessly connect with the graphene lattice, forming a planar structure distinct by a wide direct bandgap. Our in-situ STEM observations further uncover that the growth of monolayer SiC within the graphene nanopore is driven by a combination of bond rotation and atom extrusion, providing new insights into the atom-by-atom self-assembly of freestanding two-dimensional (2D) monolayers.

Select

Symmetry quantification and segmentation in STEM imaging through Zernike moments Jiadong Dan, Cheng Zhang, Xiaoxu Zhao(赵晓续), and N. Duane Loh Chin. Phys. B, 2024, 33 (8):  086803.  DOI: 10.1088/1674-1056/ad51f4 Abstract ( 168 )   HTML ( 9 )   PDF (4251KB) ( 122 )   We present a method using Zernike moments for quantifying rotational and reflectional symmetries in scanning transmission electron microscopy (STEM) images, aimed at improving structural analysis of materials at the atomic scale. This technique is effective against common imaging noises and is potentially suited for low-dose imaging and identifying quantum defects. We showcase its utility in the unsupervised segmentation of polytypes in a twisted bilayer TaS${}_2$, enabling accurate differentiation of structural phases and monitoring transitions caused by electron beam effects. This approach enhances the analysis of structural variations in crystalline materials, marking a notable advancement in the characterization of structures in materials science.

SPECIAL TOPIC — Quantum communication and quantum network

Select

Machine-learning-assisted efficient reconstruction of the quantum states generated from the Sagnac polarization-entangled photon source Menghui Mao(毛梦辉), Wei Zhou(周唯), Xinhui Li(李新慧), Ran Yang(杨然), Yan-Xiao Gong(龚彦晓), and Shi-Ning Zhu(祝世宁) Chin. Phys. B, 2024, 33 (8):  080301.  DOI: 10.1088/1674-1056/ad51f7 Abstract ( 191 )   HTML ( 6 )   PDF (4619KB) ( 233 )   Neural networks are becoming ubiquitous in various areas of physics as a successful machine learning (ML) technique for addressing different tasks. Based on ML technique, we propose and experimentally demonstrate an efficient method for state reconstruction of the widely used Sagnac polarization-entangled photon source. By properly modeling the target states, a multi-output fully connected neural network is well trained using only six of the sixteen measurement bases in standard tomography technique, and hence our method reduces the resource consumption without loss of accuracy. We demonstrate the ability of the neural network to predict state parameters with a high precision by using both simulated and experimental data. Explicitly, the mean absolute error for all the parameters is below 0.05 for the simulated data and a mean fidelity of 0.99 is achieved for experimentally generated states. Our method could be generalized to estimate other kinds of states, as well as other quantum information tasks.

SPECIAL TOPIC — Quantum computing and quantum sensing

Select

A family of quantum von Neumann architecture Dong-Sheng Wang(王东升) Chin. Phys. B, 2024, 33 (8):  080302.  DOI: 10.1088/1674-1056/ad50be Abstract ( 201 )   HTML ( 1 )   PDF (567KB) ( 174 )   We develop universal quantum computing models that form a family of quantum von Neumann architectures, with modular units of memory, control, CPU, and internet, besides input and output. This family contains three generations characterized by dynamical quantum resource theory, and it also circumvents no-go theorems on quantum programming and control. Besides universality, such a family satisfies other desirable engineering requirements on system and algorithm design, such as modularity and programmability, hence serves as a unique approach to building universal quantum computers.

Select

Nonlinear time-reversal interferometry with arbitrary quadratic collective-spin interaction Zhiyao Hu(胡知遥), Qixian Li(李其贤), Xuanchen Zhang(张轩晨), He-Bin Zhang(张贺宾), Long-Gang Huang(黄龙刚), and Yong-Chun Liu(刘永椿) Chin. Phys. B, 2024, 33 (8):  080601.  DOI: 10.1088/1674-1056/ad4ff7 Abstract ( 221 )   HTML ( 0 )   PDF (10363KB) ( 159 )   Atomic nonlinear interferometry has wide applications in quantum metrology and quantum information science. Here we propose a nonlinear time-reversal interferometry scheme with high robustness and metrological gain based on the spin squeezing generated by arbitrary quadratic collective-spin interaction, which could be described by the Lipkin-Meshkov-Glick (LMG) model. We optimize the squeezing process, encoding process, and anti-squeezing process, finding that the two particular cases of the LMG model, one-axis twisting and two-axis twisting outperform in robustness and precision, respectively. Moreover, we propose a Floquet driving method to realize equivalent time reverse in the atomic system, which leads to high performance in precision, robustness, and operability. Our study sets a benchmark for achieving high precision and high robustness in atomic nonlinear interferometry.

DATA PAPER

Select

Electron capture and excitation in intermediate-energy He2+-H(1s,2s) collisions Yadong Liu(刘亚东), Congcong Jia(贾聪聪), Mingxuan Ma(马茗萱), Xiang Gao(高翔), Ling Liu(刘玲), Yong Wu(吴勇), Xiangjun Chen(陈向军), and Jianguo Wang(王建国) Chin. Phys. B, 2024, 33 (8):  083401.  DOI: 10.1088/1674-1056/ad5322 Abstract ( 158 )   HTML ( 2 )   PDF (947KB) ( 99 )   The semiclassical non-perturbative atomic orbital close-coupling approach has been employed to study the electron capture and excitation processes in He${}^{2+}$-H(1s) and He${}^{2+}$-H(2s) collision systems. In order to ensure the accuracy of our calculated cross sections, a large number of high excited states and pseudostates are included in the expansion basis sets which are centered on the target and projectile, respectively. The total and partial charge transfer and excitation cross sections are obtained for a wide-energy domain ranging from 1 keV/amu to 200 keV/amu. The present calculations are also compared with the results from other theoretical methods. These cross section data are useful for the investigation of astrophysics and laboratory plasma.

Select

Physics-embedded machine learning search for Sm-doped PMN-PT piezoelectric ceramics with high performance Rui Xin(辛睿), Yaqi Wang(王亚祺), Ze Fang(房泽), Fengji Zheng(郑凤基), Wen Gao(高雯), Dashi Fu(付大石), Guoqing Shi(史国庆), Jian-Yi Liu(刘建一), and Yongcheng Zhang(张永成) Chin. Phys. B, 2024, 33 (8):  087701.  DOI: 10.1088/1674-1056/ad51f3 Abstract ( 151 )   HTML ( 1 )   PDF (818KB) ( 92 )   Pb(Mg${}_{1/3}$Nb${}_{2/3}$)O${}_3$-PbTiO${}_3$ (PMN-PT) piezoelectric ceramics have excellent piezoelectric properties and are used in a wide range of applications. Adjusting the solid solution ratios of PMN/PT and different concentrations of elemental doping are the main methods to modulate their piezoelectric coefficients. The combination of these controllable conditions leads to an exponential increase of possible compositions in ceramics, which makes it not easy to extend the sample data by additional experimental or theoretical calculations. In this paper, a physics-embedded machine learning method is proposed to overcome the difficulties in obtaining piezoelectric coefficients and Curie temperatures of Sm-doped PMN-PT ceramics with different components. In contrast to all-data-driven model, physics-embedded machine learning is able to learn nonlinear variation rules based on small datasets through potential correlation between ferroelectric properties. Based on the model outputs, the positions of morphotropic phase boundary (MPB) with different Sm doping amounts are explored. We also find the components with the best piezoelectric property and comprehensive performance. Moreover, we set up a database according to the obtained results, through which we can quickly find the optimal components of Sm-doped PMN-PT ceramics according to our specific needs.

RAPID COMMUNICATION

Select

Mode coupling with Fabry-Perot modes in photonic crystal slabs Hot! Ken Qin(秦恳), Peng Hu(胡鹏), Jie Liu(刘杰), Hong Xiang(向红), and De-Zhuan Han(韩德专) Chin. Phys. B, 2024, 33 (8):  084205.  DOI: 10.1088/1674-1056/ad4ff8 Abstract ( 225 )   HTML ( 4 )   PDF (763KB) ( 227 )   Fabry-Perot (FP) modes are a class of fundamental resonances in photonic crystal (PhC) slabs. Owing to their low quality factors, FP modes are frequently considered as background fields with their resonance nature being neglected. Nevertheless, FP modes can play important roles in some phenomena, as exemplified by their coupling with guided resonance (GR) modes to achieve bound states in the continuum (BIC). Here, we further demonstrate the genuine resonance mode capability of FP modes PhC slabs. Firstly, we utilize temporal coupled-mode theory to obtain the transmittance of a PhC slab based on the FP modes. Secondly, we construct exceptional points (EPs) in both momentum and parameter spaces through the coupling of FP and GR modes. Furthermore, we identify a Fermi arc connecting two EPs and discuss the far-field polarization topology. This work elucidates that the widespread FPs in PhC slabs can serve as genuine resonant modes, facilitating the realization of desired functionalities through mode coupling.

Select

Comparative study of nudged elastic band and molecular dynamics methods for diffusion kinetics in solid-state electrolytes Hot! Aming Lin(林啊鸣), Jing Shi(石晶), Su-Huai Wei(魏苏淮), and Yi-Yang Sun(孙宜阳) Chin. Phys. B, 2024, 33 (8):  086601.  DOI: 10.1088/1674-1056/ad5d9a Abstract ( 218 )   HTML ( 4 )   PDF (1423KB) ( 181 )   Considerable efforts are being made to transition current lithium-ion and sodium-ion batteries towards the use of solid-state electrolytes. Computational methods, specifically nudged elastic band (NEB) and molecular dynamics (MD) methods, provide powerful tools for the design of solid-state electrolytes. The MD method is usually the choice for studying the materials involving complex multiple diffusion paths or having disordered structures. However, it relies on simulations at temperatures much higher than working temperature. This paper studies the reliability of the MD method using the system of Na diffusion in MgO as a benchmark. We carefully study the convergence behavior of the MD method and demonstrate that total effective simulation time of 12 ns can converge the calculated diffusion barrier to about 0.01 eV. The calculated diffusion barrier is 0.31 eV from both methods. The diffusion coefficients at room temperature are $4.3\times {10}^{-9}$ cm${}^2\cdot$s${}^{-1}$ and $2.2\times {10}^{-9}$ cm${}^2\cdot$s${}^{-1}$, respectively, from the NEB and MD methods. Our results justify the reliability of the MD method, even though high temperature simulations have to be employed to overcome the limitation on simulation time.

Select

Manipulation of band gap in 1T-TiSe2 via rubidium deposition Hot! Yi Ou(欧仪), Lei Chen(陈磊), Zi-Ming Xin(信子鸣), Yu-Jing Ren(任宇靖), Peng-Hao Yuan(袁鹏浩), Zheng-Guo Wang(王政国), Yu Zhu(朱玉), Jing-Zhi Chen(陈景芝), and Yan Zhang(张焱) Chin. Phys. B, 2024, 33 (8):  087401.  DOI: 10.1088/1674-1056/ad48f9 Abstract ( 406 )   HTML ( 224 )   PDF (954KB) ( 398 )   The 1$T$-TiSe${}_2$ is a two-dimensional charge-density-wave (CDW) material that attracts great interest. A small band gap locates at the Fermi level separating the Ti d-bands and Se p-bands, which makes 1$T$-TiSe${}_2$ a promising candidate for realizing excitonic condensation. Here, we studied the band gap in 1$T$-TiSe${}_2$ using angle-resolved photoemission spectroscopy (ARPES). Instead of only focusing on the in-plane band dispersions, we obtained the detailed band dispersions of both conduction and valance bands along the out-of-plane direction. We found that the conduction and valance bands split into multiple sub-bands in the CDW state due to band folding. As a result, the band gap between the Ti d-bands and Se p-bands reduces to $\sim 25$ meV and becomes a direct gap in the CDW state. More intriguingly, such band gap can be further reduced by the rubidium deposition. The band structure becomes semimetallic in the rubidium-doped sample. Meanwhile, exotic gapless behaviors were observed at the p-d band crossing. Our result characterized the band gap of 1$T$-TiSe${}_2$ in three-dimensional Brillouin zone with unpreceded precision. It also suggests a closing of band gap or a potential band inversion in 1$T$-TiSe${}_2$ driven by rubidium deposition.

Select

Deep-subwavelength single grooves prepared by femtosecond laser direct writing on Si Rui-Xi Ye(叶瑞熙) and Min Huang(黄敏) Chin. Phys. B, 2024, 33 (8):  087901.  DOI: 10.1088/1674-1056/ad4cd6 Abstract ( 140 )   HTML ( 1 )   PDF (6865KB) ( 94 )   It is well known that femtosecond laser pulses can easily spontaneously induce deep-subwavelength periodic surface structures on transparent dielectrics but not on non-transparent semiconductors. Nevertheless, in this study, we demonstrate that using high-numerical-aperture 800 nm femtosecond laser direct writing with controlled pulse energy and scanning speed in the near-damage-threshold regime, polarization-dependent deep-subwavelength single grooves with linewidths of $\sim 180$ nm can be controllably prepared on Si. Generally, the single-groove linewidth increases slightly with increase in the pulse energy and decrease in the scanning speed, whereas the single-groove depth significantly increases from $\sim 300$ nm to $\sim 600$ nm with decrease in the scanning speed, or even to over 1 μm with multi-processing, indicating the characteristics of transverse clamping and longitudinal growth of such deep-subwavelength single grooves. Energy dispersive spectroscopy composition analysis of the near-groove region confirms that single-groove formation tends to be an ultrafast, non-thermal ablation process, and the oxidized deposits near the grooves are easy to clean up. Furthermore, the results, showing both the strong dependence of groove orientation on laser polarization and the occurrence of double-groove structures due to the interference of pre-formed orthogonal grooves, indicate that the extraordinary field enhancement of strong polarization sensitivity in the deep-subwavelength groove plays an important role in single-groove growth with high stability and collimation.

Select

Interface and mechanical degradation mechanisms of the silicon anode in sulfide-based solid-state batteries at high temperatures Hot! Qiuchen Wang(王秋辰), Yuli Huang(黄昱力), Jing Xu(许晶), Xiqian Yu(禹习谦), Hong Li(李泓), and Liquan Chen(陈立泉) Chin. Phys. B, 2024, 33 (8):  088201.  DOI: 10.1088/1674-1056/ad5276 Abstract ( 221 )   HTML ( 0 )   PDF (3381KB) ( 231 )   Silicon (Si) is a competitive anode material owing to its high theoretical capacity and low electrochemical potential. Recently, the prospect of Si anodes in solid-state batteries (SSBs) has been proposed due to less solid electrolyte interphase (SEI) formation and particle pulverization. However, major challenges arise for Si anodes in SSBs at elevated temperatures. In this work, the failure mechanisms of Si-Li${}_6$PS${}_5$Cl (LPSC) composite anodes above 80 ${}^{\circ }$C are thoroughly investigated from the perspectives of interface stability and (electro)chemo-mechanical effect. The chemistry and growth kinetics of Li${}_x$Si$|$LPSC interphase are demonstrated by combining electrochemical, chemical and computational characterizations. Si and/or Si-P compound formed at Li${}_x$Si$|$LPSC interface prove to be detrimental to interface stability at high temperatures. On the other hand, excessive volume expansion and local stress caused by Si lithiation at high temperatures damage the mechanical structure of Si-LPSC composite anodes. This work elucidates the behavior and failure mechanisms of Si-based anodes in SSBs at high temperatures and provides insights into upgrading Si-based anodes for application in SSBs.

Select

Surface encapsulation of layered oxide cathode material with NiTiO3 for enhanced cycling stability of Na-ion batteries Hot! Zilin Hu(胡紫霖), Bin Tang(唐彬), Ting Lin(林挺), Chu Zhang(张楚), Yaoshen Niu(牛耀申), Yuan Liu(刘渊), Like Gao(高立克), Fei Xie(谢飞), Xiaohui Rong(容晓晖), Yaxiang Lu(陆雅翔), and Yongsheng Hu(胡勇胜) Chin. Phys. B, 2024, 33 (8):  088202.  DOI: 10.1088/1674-1056/ad50c2 Abstract ( 260 )   HTML ( 11 )   PDF (2399KB) ( 283 )   In Na-ion batteries, O3-type layered oxide cathode materials encounter challenges such as particle cracking, oxygen loss, electrolyte side reactions, and multi-phase transitions during the charge/discharge process. This study focuses on surface coating with NiTiO${}_3$ achieved via secondary heat treatment using a coating precursor and the surface material. Through in-situ x-ray diffraction (XRD) and differential electrochemical mass spectrometry (DEMS), along with crystal structure characterizations of post-cycling materials, it was determined that the NiTiO${}_3$ coating layer facilitates the formation of a stable lattice structure, effectively inhibiting lattice oxygen loss and reducing side reaction with the electrolyte. This enhancement in cycling stability was evidenced by a capacity retention of approximately 74% over 300 cycles at 1 C, marking a significant 30% improvement over the initial sample. Furthermore, notable advancements in rate performance were observed. Experimental results indicate that a stable and robust surface structure substantially enhances the overall stability of the bulk phase, presenting a novel approach for designing layered oxide cathodes with higher energy density.

Select

Piezoelectric fibers based on silk fibroin with excellent output performance Hot! Wenqiang Zhen(甄文强), Jie Chen(陈杰), Suna Fan(范苏娜), and Yaopeng Zhang(张耀鹏) Chin. Phys. B, 2024, 33 (8):  088701.  DOI: 10.1088/1674-1056/ad51f5 Abstract ( 202 )   HTML ( 7 )   PDF (1722KB) ( 118 )   The self-powered tissue engineering scaffold with good biocompatibility is of great significance for stimulating nerve cell growth. In this study, silk fibroin (SF)-based fibers with regulatable structure and piezoelectric performance are fabricated by dry-spinning and post-treatment. The concentration of SF and calcium ion in spinning dope and the post-treatment affect the conformation transition and crystallinity of SF. As a result, the SF fibers exhibit high piezoelectric coefficient $d_{33}$ (3.24 pm/V) and output voltage ($\sim 27$ V). Furthermore, these piezoelectric fibers promote the growth of PC-12 cells, demonstrating the promising potential for nerve repair and other energy harvester.

GENERAL

Select

Multi-soliton solutions of coupled Lakshmanan-Porsezian-Daniel equations with variable coefficients under nonzero boundary conditions Hui-Chao Zhao(赵会超), Lei-Nuo Ma(马雷诺), and Xi-Yang Xie(解西阳) Chin. Phys. B, 2024, 33 (8):  080201.  DOI: 10.1088/1674-1056/ad4d64 Abstract ( 203 )   HTML ( 1 )   PDF (6225KB) ( 98 )   This paper aims to investigate the multi-soliton solutions of the coupled Lakshmanan-Porsezian-Daniel equations with variable coefficients under nonzero boundary conditions. These equations are utilized to model the phenomenon of nonlinear waves propagating simultaneously in non-uniform optical fibers. By analyzing the Lax pair and the Riemann-Hilbert problem, we aim to provide a comprehensive understanding of the dynamics and interactions of solitons of this system. Furthermore, we study the impacts of group velocity dispersion or the fourth-order dispersion on soliton behaviors. Through appropriate parameter selections, we observe various nonlinear phenomena, including the disappearance of solitons after interaction and their transformation into breather-like solitons, as well as the propagation of breathers with variable periodicity and interactions between solitons with variable periodicities.

Select

Topological phases and edge modes of an uneven ladder Wen-Chuang Shang(商文创), Yi-Ning Han(韩熠宁), Shimpei Endo, and Chao Gao(高超) Chin. Phys. B, 2024, 33 (8):  080202.  DOI: 10.1088/1674-1056/ad50c0 Abstract ( 191 )   HTML ( 0 )   PDF (4899KB) ( 116 )   We investigate the topological properties of a two-chain quantum ladder with uneven legs, i.e., the two chains differ in their periods by a factor of 2. Such an uneven ladder presents rich band structures classified by the closure of either direct or indirect bandgaps. It also provides opportunities to explore fundamental concepts concerning band topology and edge modes, including the difference of intracellular and intercellular Zak phases, and the role of the inversion symmetry (IS). We calculate the Zak phases of the two kinds and find excellent agreement with the dipole moment and extra charge accumulation. We also find that configurations with IS feature a pair of degenerate two-side edge modes emerging as the closure of the direct bandgap, while configurations without IS feature one-side edge modes emerging as not only the closure of both direct and indirect bandgaps but also within the band continuum. Furthermore, by projecting to the two sublattices, we find that the effective Bloch Hamiltonian corresponds to that of a generalized Su-Schrieffer-Heeger model or the Rice-Mele model whose hopping amplitudes depend on the quasimomentum. In this way, the topological phases can be efficiently extracted through winding numbers. We propose that uneven ladders can be realized by spin-dependent optical lattices and their rich topological characteristics can be examined by near future experiments.

Select

Massive Dirac particles based on gapped graphene with Rosen-Morse potential in a uniform magnetic field A. Kalani, Alireza Amani, and M. A. Ramzanpour Chin. Phys. B, 2024, 33 (8):  080303.  DOI: 10.1088/1674-1056/ad426b Abstract ( 189 )   HTML ( 0 )   PDF (576KB) ( 72 )   We explore the gapped graphene structure in the two-dimensional plane in the presence of the Rosen-Morse potential and an external uniform magnetic field. In order to describe the corresponding structure, we consider the propagation of electrons in graphene as relativistic fermion quasi-particles, and analyze it by the wave functions of two-component spinors with pseudo-spin symmetry using the Dirac equation. Next, to solve and analyze the Dirac equation, we obtain the eigenvalues and eigenvectors using the Legendre differential equation. After that, we obtain the bounded states of energy depending on the coefficients of Rosen-Morse and magnetic potentials in terms of quantum numbers of principal $n$ and spin-orbit $k$. Then, the values of the energy spectrum for the ground state and the first excited state are calculated, and the wave functions and the corresponding probabilities are plotted in terms of coordinates $r$. In what follows, we explore the band structure of gapped graphene by the modified dispersion relation and write it in terms of the two-dimensional wave vectors $K_x$ and $K_y$. Finally, the energy bands are plotted in terms of the wave vectors $K_x$ and $K_y$ with and without the magnetic term.

Select

New construction of mutually unbiased bases for odd-dimensional state space Chenghong Wang(王成红), Kun Wang(王昆), and Zhu-Jun Zheng(郑驻军) Chin. Phys. B, 2024, 33 (8):  080304.  DOI: 10.1088/1674-1056/ad47ae Abstract ( 185 )   HTML ( 0 )   PDF (452KB) ( 48 )   We study the construction of mutually unbiased bases in Hilbert space for composite dimensions $d$ which are not prime powers. We explore the results for composite dimensions which are true for prime power dimensions. We then provide a method for selecting mutually unbiased vectors from the eigenvectors of generalized Pauli matrices to construct mutually unbiased bases. In particular, we present four mutually unbiased bases in ${\mathbb{C}}^{15}$.

Select

Micron-sized fiber diamond probe for quantum precision measurement of microwave magnetic field Wen-Tao Lu(卢文韬), Sheng-Kai Xia(夏圣开), Ai-Qing Chen(陈爱庆), Kang-Hao He(何康浩), Zeng-Bo Xu(许增博), Yi-Han Chen(陈艺涵), Yang Wang(汪洋), Shi-Yu Ge(葛仕宇), Si-Han An(安思瀚), Jian-Fei Wu(吴建飞), Yi-Han Ma(马艺菡), and Guan-Xiang Du(杜关祥) Chin. Phys. B, 2024, 33 (8):  080305.  DOI: 10.1088/1674-1056/ad5321 Abstract ( 240 )   HTML ( 4 )   PDF (2520KB) ( 119 )   We present a quantitative measurement of the horizontal component of the microwave magnetic field of a coplanar waveguide using a quantum diamond probe in fiber format. The measurement results are compared in detail with simulation, showing a good consistence. Further simulation shows fiber diamond probe brings negligible disturbance to the field under measurement compared to bulk diamond. This method will find important applications ranging from electromagnetic compatibility test and failure analysis of high frequency and high complexity integrated circuits.

Select

Security analysis of satellite-to-ground reference-frame-independent quantum key distribution with beam wandering Chun Zhou(周淳), Yan-Mei Zhao(赵燕美), Xiao-Liang Yang(杨晓亮), Yi-Fei Lu(陆宜飞), Yu Zhou(周雨), Xiao-Lei Jiang(姜晓磊), Hai-Tao Wang(汪海涛), Yang Wang(汪洋), Jia-Ji Li(李家骥), Mu-Sheng Jiang(江木生), Xiang Wang(汪翔), Hai-Long Zhang(张海龙), Hong-Wei Li(李宏伟), and Wan-Su Bao(鲍皖苏) Chin. Phys. B, 2024, 33 (8):  080306.  DOI: 10.1088/1674-1056/ad51f6 Abstract ( 141 )   HTML ( 0 )   PDF (853KB) ( 179 )   The reference-frame-independent (RFI) quantum key distribution (QKD) is suitable for satellite-based links by removing the active alignment on the reference frames. However, how the beam wandering influences the performance of RFI-QKD remains a pending issue in satellite-to-ground links. In this paper, based on the mathematical model for characterizing beam wandering, we present the security analysis for satellite-to-ground RFI-QKD and analytically derive formulas for calculating the secret key rate with beam wandering. Our simulation results show that the performance of RFI-QKD is better than the Bennett-Brassard 1984 (BB84) QKD with beam wandering in asymptotic case. Furthermore, the degree of influences of beam wandering is specifically presented for satellite-to-ground RFI-QKD when statistical fluctuations are taken into account. Our work can provide theoretical support for the realization of RFI-QKD using satellite-to-ground links and have implications for the construction of large-scale satellite-based quantum networks.

Select

Effects of quantum noise on teleportation of arbitrary two-qubit state via five-particle Brown state Ao Wang(汪澳), Yu-Zhen Wei(魏玉震), Min Jiang(姜敏), Yong-Cheng Li(李泳成), Hong Chen(陈虹), and Xu Huang(黄旭) Chin. Phys. B, 2024, 33 (8):  080307.  DOI: 10.1088/1674-1056/ad3dc8 Abstract ( 179 )   HTML ( 1 )   PDF (1243KB) ( 48 )   We propose a new protocol for quantum teleportation (QT) which adopts the Brown state as the quantum channel. This work focuses on the teleportation of a single unknown two-qubit state via a Brown state channel in an ideal environment. To validate the effectiveness of our proposed scheme, we conduct experiments by using the quantum circuit simulator Quirk. Furthermore, we investigate the effects of four noisy channels, namely, the phase damping noise, the bit-flip noise, the amplitude damping noise, and the phase-flip noise. Notably, we employ Monte Carlo simulation to elucidate the fidelity density under various noise parameters. Our analysis demonstrates that the fidelity of the protocol in a noisy environment is influenced significantly by the amplitude of the initial state and the noise factor.

Select

Quantum block coherence with respect to projective measurements Pu Wang(王璞), Zhong-Yan Li(李忠艳), and Hui-Xian Meng(孟会贤) Chin. Phys. B, 2024, 33 (8):  080308.  DOI: 10.1088/1674-1056/ad50c1 Abstract ( 144 )   HTML ( 1 )   PDF (534KB) ( 77 )   Quantum coherence serves as a defining characteristic of quantum mechanics, finding extensive applications in quantum computing and quantum communication processing. This study explores quantum block coherence in the context of projective measurements, focusing on the quantification of such coherence. Firstly, we define the correlation function between the two general projective measurements $P$ and $Q$, and analyze the connection between sets of block incoherent states related to two compatible projective measurements $P$ and $Q$. Secondly, we discuss the measure of quantum block coherence with respect to projective measurements. Based on a given measure of quantum block coherence, we characterize the existence of maximal block coherent states through projective measurements. This research integrates the compatibility of projective measurements with the framework of quantum block coherence, contributing to the advancement of block coherence measurement theory.

Select

Detecting short-term gravitational waves from post-merger hyper-massive neutron stars with a kilohertz detector Yikang Chen(陈奕康) and Zong-Hong Zhu(朱宗宏) Chin. Phys. B, 2024, 33 (8):  080401.  DOI: 10.1088/1674-1056/ad5320 Abstract ( 113 )   HTML ( 0 )   PDF (887KB) ( 33 )   Gravitational waves emanating from binary neutron star inspirals, alongside electromagnetic transients resulting from the aftermath of the GW170817 merger, have been successfully detected. However, the intricate post-merger dynamics that bridge these two sets of observables remain enigmatic. This includes if, and when, the post-merger remnant star collapses to a black hole, and what are the necessary conditions to power a short gamma-ray burst, and other observed electromagnetic counterparts. Our focus is on the detection of gravitational wave (GW) emissions from hyper-massive neutron stars (NSs) formed through binary neutron star (BNS) mergers. Utilizing several kilohertz GW detectors, we simulate BNS mergers within the detection limits of LIGO-Virgo-KARGA O4. Our objective is to ascertain the fraction of simulated sources that may emit detectable post-merger GW signals. For kilohertz detectors equipped with a new cavity design, we estimate that approximately 1.1%-32% of sources would emit a detectable post-merger GW signal. This fraction is contingent on the mass converted into gravitational wave energy, ranging from $0.01M_{\mathrm{s}\mathrm{u}\mathrm{n}}$ to $0.1M_{\mathrm{s}\mathrm{u}\mathrm{n}}$. Furthermore, by evaluating other well-regarded proposed kilohertz GW detectors, we anticipate that the fraction can increase to as much as 2.1%-61% under optimal performance conditions.

Select

Deep learning-assisted common temperature measurement based on visible light imaging Jia-Yi Zhu(朱佳仪), Zhi-Min He(何志民), Cheng Huang(黄成), Jun Zeng(曾峻), Hui-Chuan Lin(林惠川), Fu-Chang Chen(陈福昌), Chao-Qun Yu(余超群), Yan Li(李燕), Yong-Tao Zhang(张永涛), Huan-Ting Chen(陈焕庭), and Ji-Xiong Pu(蒲继雄) Chin. Phys. B, 2024, 33 (8):  080701.  DOI: 10.1088/1674-1056/ad4cd9 Abstract ( 257 )   HTML ( 3 )   PDF (1846KB) ( 148 )   Real-time, contact-free temperature monitoring of low to medium range (30 ${}^{\circ }$C-150 ${}^{\circ }$C) has been extensively used in industry and agriculture, which is usually realized by costly infrared temperature detection methods. This paper proposes an alternative approach of extracting temperature information in real time from the visible light images of the monitoring target using a convolutional neural network (CNN). A mean-square error of $<{1.119}^{\circ }$C was reached in the temperature measurements of low to medium range using the CNN and the visible light images. Imaging angle and imaging distance do not affect the temperature detection using visible optical images by the CNN. Moreover, the CNN has a certain illuminance generalization ability capable of detection temperature information from the images which were collected under different illuminance and were not used for training. Compared to the conventional machine learning algorithms mentioned in the recent literatures, this real-time, contact-free temperature measurement approach that does not require any further image processing operations facilitates temperature monitoring applications in the industrial and civil fields.

ATOMIC AND MOLECULAR PHYSICS

Select

All-electron basis sets for H to Xe specific for ZORA calculations: Applications in atoms and molecules C. S. Gomes, F. E. Jorge, and A. Canal Neto Chin. Phys. B, 2024, 33 (8):  083101.  DOI: 10.1088/1674-1056/ad4bbe Abstract ( 96 )   HTML ( 0 )   PDF (859KB) ( 53 )   A segmented basis set of quadruple zeta valence quality plus polarization functions (QZP) for H through Xe was developed to be used in conjunction with the ZORA Hamiltonian. This set was augmented with diffuse functions to describe electrons farther away from the nuclei adequately. Using the ZORA-CCSD(T)/QZP-ZORA theoretical model, atomic ionization energies and bond lengths, harmonic vibrational frequencies, and atomization energies of some molecules were calculated. The addition of core-valence corrections has been shown to improve the agreement between theoretical and experimental results for molecular properties. For atomization energies, a similar observation emerges when considering spin-orbit couplings. With the augmented QZP-ZORA set, static mean dipole polarizabilities of a set of atoms were calculated and compared with previously published recommended and experimental values. Performance evaluations of the ZORA and Douglas-Kroll-Hess Hamiltonians were made for each property studied.

Select

Steering the energy sharing of electrons in nonsequential double ionization with orthogonally polarized two-color field Guangqi Fan(樊光琦), Zhijie Yang(杨志杰), Fenghao Sun(孙烽豪), Jinmei Zheng(郑金梅), Yuntian Han(韩云天), Mingqian Huang(黄明谦), and Qingcao Liu(刘情操) Chin. Phys. B, 2024, 33 (8):  083102.  DOI: 10.1088/1674-1056/ad4bc0 Abstract ( 186 )   HTML ( 3 )   PDF (1500KB) ( 60 )   Using the semiclassical ensemble model, the dependence of relative amplitude for the recollision dynamics in nonsequential double ionization (NSDI) of neon atom driven by the orthogonally polarized two-color field (OTC) laser field is theoretically studied. And the dynamics in two typical collision pathways, recollision-impact-ionization (RII) and recollision-excitation with subsequent ionization (RESI), is systematically explored. Our results reveal that the V-shaped structure in the correlated momentum distribution is mainly caused by the RII mechanism when the relative amplitude of the OTC laser field is zero, and the first ionized electrons will quickly skim through the nucleus and share few energy with the second electron. As the relative amplitude increases, the V-shaped structure gradually disappears and electrons are concentrated on the diagonal in the electron correlation spectrum, indicating that the energy sharing after electrons collision is symmetric for OTC laser fields with large relative amplitudes. Our studies show that changing the relative amplitude of the OTC laser field can efficiently control the electron-electron collisions and energy exchange efficiency in the NSDI process.

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

Select

Surface phonon resonance: A new mechanism for enhancing photonic spin Hall effect and refractive index sensor Jie Cheng(程杰), Chenglong Wang(汪承龙), Yiming Li(李一铭), Yalin Zhang(张亚林), Shengli Liu(刘胜利), and Peng Dong(董鹏) Chin. Phys. B, 2024, 33 (8):  084201.  DOI: 10.1088/1674-1056/ad4a3c Abstract ( 124 )   HTML ( 0 )   PDF (1460KB) ( 68 )   Metal-based surface plasmon resonance (SPR) plays an important role in enhancing the photonic spin Hall effect (SHE) and developing sensitive optical sensors. However, the very large negative permittivities of metals limit their applications beyond the near-infrared regime. In this work, we theoretically present a new mechanism to enhance the photonic SHE by taking advantage of SiC-supported surface phonon resonance (SPhR) in the mid-infrared regime. The transverse displacement of photonic SHE is very sensitive to the wavelength of incident light and the thickness of SiC layer. Under the optimal parameter setup, the calculated largest transverse displacement of SiC-based SPhR structure reaches up to 163.8 μm, which is much larger than the condition of SPR. Moreover, an NO${}_2$ gas sensor based on the SPhR-enhanced photonic SHE is theoretically proposed with the superior sensing performance. Both the intensity and angle sensitivity of this sensor can be effectively manipulated by varying the damping rate of SiC. The results may provide a promising paradigm to enhance the photonic SHE in the mid-infrared region and open up new opportunity of highly sensitive refractive index sensors.

Select

Optical storage of circular airy beam in atomic vapor Hong Chang(常虹), Xin Yang(杨欣), Yan Ma(马燕), Xinqi Yang(杨鑫琪), Mingtao Cao(曹明涛), Xiaofei Zhang(张晓斐), Ruifang Dong(董瑞芳), and Shougang Zhang(张首刚) Chin. Phys. B, 2024, 33 (8):  084202.  DOI: 10.1088/1674-1056/ad4bbf Abstract ( 163 )   HTML ( 2 )   PDF (1762KB) ( 161 )   The realization of quantum storage of spatial light field is of great significance to the construction of high-dimensional quantum repeater. In this paper, we experimentally realize the storage and retrieval of circular Airy beams (CABs) by using the $\Lambda$-type three-level energy system based on the electromagnetically induced transparency in a hot rubidium atomic vapor cell. The weak probe beam field is modulated with phase distribution of CABs by a spatial light modulator. We store the probe circular Airy beam (CAB) into the rubidium atomic vapor cell and retrieve it after the demanded delay. We quantitatively analyze the storage results and give corresponding theoretical explanations. Moreover, we investigate the autofocusing and self-healing effect of the retrieved CAB, which indicates that the properties and beam shape of CAB maintain well after storage. Our work will have potential applications in the storage of high-dimensional quantum information, and is also useful for improving the channel capacities of quantum internet.

Select

Enhanced picosecond terahertz wave generation based on cascade effects in a terahertz parametric generator Jingxi Zhang(张敬喜), Yuye Wang(王与烨), Bingfeng Xu(徐炳烽), Kai Chen(陈锴), Zikun Liu(刘紫鲲), Hongru Ma(马鸿儒), Degang Xu(徐德刚), and Jianquan Yao(姚建铨) Chin. Phys. B, 2024, 33 (8):  084203.  DOI: 10.1088/1674-1056/ad47b0 Abstract ( 133 )   HTML ( 2 )   PDF (2354KB) ( 93 )   Enhanced terahertz wave generation via a Stokes cascade process has been demonstrated using picosecond pulse pumped terahertz parametric generation at 1 kHz repetition rate. Clear cascade saturation of terahertz output was observed, and the corresponding cascade-Stokes spectra were analyzed. The maximum terahertz wave average power was 22 μW under a pump power of 30 W, whereas the maximum power conversion efficiency was 8$\times {10}^{-7}$ under a pump power of 21 W. The THz power fluctuation was measured to be about 1% in 20 min. This THz parametric source with a relatively stable output is suitable for a variety of practical applications.

Select

Design of a high sensitivity and wide range angular rate sensor based on exceptional surface Xinsheng Ding(丁鑫圣), Wenyao Liu(刘文耀), Shixian Wang(王师贤), Yu Tao(陶煜), Yanru Zhou(周彦汝), Yu Bai(白禹), Lai Liu(刘来), Enbo Xing(邢恩博), Jun Tang(唐军), and Jun Liu(刘俊) Chin. Phys. B, 2024, 33 (8):  084204.  DOI: 10.1088/1674-1056/ad4324 Abstract ( 138 )   HTML ( 0 )   PDF (2969KB) ( 93 )   It is found that when the parity-time symmetry phenomenon is introduced into the resonant optical gyro system and it works near the exceptional point, the sensitivity can in theory be significantly amplified at low angular rate. However, in fact, the exceptional point is easily disturbed by external environmental variables, which means that it depends on harsh experimental environment and strong control ability, so it is difficult to move towards practical application. Here, we propose a new angular rate sensor structure based on exceptional surface, which has the advantages of high sensitivity and high robustness. The system consists of two fiber-optic ring resonators and two optical loop mirrors, and one of the resonators contains a variable ratio coupler and a variable optical attenuator. We theoretically analyze the system response, and the effects of phase and coupling ratio on the system response. Finally, compared with the conventional resonant gyro, the sensitivity of this exceptional surface angular rate sensor can be improved by about 300 times at low speed. In addition, by changing the loss coefficient in the ring resonator, we can achieve a wide range of 600 rad/s. This scheme provides a new approach for the development of ultra-high sensitivity and wide range angular rate sensors in the future.

Select

Interface state-based bound states in continuum and below-continuum-resonance modes with high-Q factors in the rotational periodic system Jialing Yang(杨嘉玲), Aoqian Shi(史奥芊), Yuchen Peng(彭宇宸), Peng Peng(彭鹏), and Jianjun Liu(刘建军) Chin. Phys. B, 2024, 33 (8):  084206.  DOI: 10.1088/1674-1056/ad4630 Abstract ( 120 )   HTML ( 0 )   PDF (1378KB) ( 128 )   We have introduced a new approach to calculate the orbital angular momentum (OAM) of bound states in continuum (BICs) and below-continuum-resonance (BCR) modes in the rotational periodic system nested inside and outside by transforming the Bloch wave number from the translational periodic system. We extensively classify and study these BICs and BCR modes, which exhibit high-quality (high-$Q$) factors, in different regions relative to the interface of the system. These BICs and BCR modes with a high-$Q$ factor have been studied in detail based on distinctive structural parameters and scattering theory. The outcomes of this research break the periodic limitation of interface state-based BICs, and realize more and higher symmetry interface state-based BICs and BCR modes. Moreover, we can control the region where light is captured by adjusting the frequency, and show that the $Q$ factor of BICs is more closely related to the ordinal number of rings and the rotational symmetry number of the system.

Select

A graph neural network approach to the inverse design for thermal transparency with periodic interparticle system Bin Liu(刘斌) and Yixi Wang(王译浠) Chin. Phys. B, 2024, 33 (8):  084401.  DOI: 10.1088/1674-1056/ad4326 Abstract ( 139 )   HTML ( 2 )   PDF (1493KB) ( 92 )   Recent years have witnessed significant advances in utilizing machine learning-based techniques for thermal metamaterial-based structures and devices to attain favorable thermal transport behaviors. Among the various thermal transport behaviors, achieving thermal transparency stands out as particularly desirable and intriguing. Our earlier work demonstrated the use of a thermal metamaterial-based periodic interparticle system as the underlying structure for manipulating thermal transport behavior and achieving thermal transparency. In this paper, we introduce an approach based on graph neural network to address the complex inverse design problem of determining the design parameters for a thermal metamaterial-based periodic interparticle system with the desired thermal transport behavior. Our work demonstrates that combining graph neural network modeling and inference is an effective approach for solving inverse design problems associated with attaining desirable thermal transport behaviors using thermal metamaterials.

Select

Influence of liquid film shape on evaporation performance of agitated thin film evaporator Xin-Qiang Gu(顾鑫强), Yao Huang(黄瑶), Kun Zou(邹鲲), and Yi-Tian Peng(彭倚天) Chin. Phys. B, 2024, 33 (8):  084701.  DOI: 10.1088/1674-1056/ad4323 Abstract ( 112 )   HTML ( 0 )   PDF (1802KB) ( 40 )   The agitated thin film evaporator (ATFE), which is known for its high efficiency, force the material to form a film through the scraping process of a scraper, followed by evaporation and purification. The complex shape of the liquid film inside the evaporator can significantly affect its evaporation capability. This work explores how change in shape of the liquid films affect the evaporation of the materials with non-Newtonian characteristics, achieved by changing the structure of the scraper. Examining the distribution of circumferential temperature, viscosity, and mass transfer of the flat liquid film shows that the film evaporates rapidly in shear-thinning region. Various wavy liquid films are developed by using shear-thinning theory, emphasizing the flow condition in the thinning area and the factors contributing to the exceptional evaporation capability. Further exploration is conducted on the spread patterns of the wavy liquid film and flat liquid film on the evaporation wall throughout the process. It is noted that breaking the wavy liquid film on the evaporating wall during evaporation is challenging due to its film-forming condition. For which the fundamental causes are demonstrated by acquiring the data regarding the flow rate and temperature of the liquid film. The definitive findings of the analysis reveal a significant improvement in the evaporation capability of the wavy liquid film. This enhancement is attributed to increasing the shear-thinning areas and maintaining the overall shape of the film throughout the entire evaporation process.

Select

Deformation and mutual influence of two cylindrical water columns in tandem subjected to shock wave Zhen-Yu Hong(洪振宇), Yang Song(宋洋), Rui Wang(王睿), Zong-Qiang Ma(马宗强), Dong-Jun Ma(马东军), and Pei Wang (王裴) Chin. Phys. B, 2024, 33 (8):  084702.  DOI: 10.1088/1674-1056/ad5273 Abstract ( 110 )   HTML ( 1 )   PDF (2479KB) ( 77 )   The interaction between shock waves and multiple cylinders, referred to as shock-cylinder interaction (SCI), is an important phenomenon in science and engineering. However, its underlying physical mechanisms remain unclear. This study entailed the numerical simulation of the aerobreakup of two tandem water columns subjected to a high-speed gas flow by using an adaptive mesh refinement (AMR)-based diffusion-interface model. The objective was to elucidate the changes in water-column deformation patterns over a wide range of Weber numbers. Statistical analysis was performed to examine the deformation of the water columns in vertical directions. Results reveal distinct deformation patterns between the two columns as the Weber number increases. Additionally, an extended exponential stretching law model was devised, and its improved capability to predict the deformation patterns was demonstrated.

Select

Integrated analysis of plasma rotation effect on HL-3 hybrid scenario Miao Xue(薛淼), Guo-Yao Zheng(郑国尧), Lei Xue(薛雷), Jia-Xian Li(李佳鲜), Shuo Wang(王硕), Hai-Long Du(杜海龙), Yi-Ren Zhu(朱毅仁), and Yue Zhou(周月) Chin. Phys. B, 2024, 33 (8):  084703.  DOI: 10.1088/1674-1056/ad43d3 Abstract ( 118 )   HTML ( 0 )   PDF (989KB) ( 73 )   The hybrid scenario, which has good confinement and moderate MHD instabilities, is a proposed operation scenario for international thermonuclear experimental reactor (ITER). In this work, the effect of plasma rotation on the HL-3 hybrid scenario is analyzed with the integrated modeling framework OMFIT. The results show that toroidal rotation has no obvious effect on confinement with a high line averaged density of $n_{\mathrm{b}\mathrm{a}\mathrm{r}}\sim 7\times {10}^{19}$ m${}^{-3}$. In this case, the ion temperature only changes from 4.7 keV to 4.4 keV with the rotation decreasing from 10${}^5$ rad/s to 10${}^3$ rad/s, which means that the turbulent heat transport is not dominant. While in the scenarios characterized by lower densities, such as $n_{\mathrm{b}\mathrm{a}\mathrm{r}}\sim 4\times {10}^{19}$ m${}^{-3}$, turbulent transport becomes dominant in determining heat transport. The ion temperature rises from 3.8 keV to 6.1 keV in the core as the rotation velocity increases from 10${}^3$ rad/s to 10${}^5$ rad/s. Despite the ion temperature rising, the rotation velocity does not obviously affect electron temperature or density. Additionally, it is noteworthy that the variation in rotation velocity does not significantly affect the global confinement of plasma in scenarios with low density or with high density.

PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

Select

Ion acoustic solitary waves in an adiabatic dusty plasma: Roles of superthermal electrons, ion loss and ionization Qianghua Rao(饶强华), Hui Chen(陈辉), Sanqiu Liu(刘三秋), and Xiaochang Chen(陈小昌) Chin. Phys. B, 2024, 33 (8):  085201.  DOI: 10.1088/1674-1056/ad47e4 Abstract ( 113 )   HTML ( 0 )   PDF (1096KB) ( 69 )   We investigate propagation of dust ion acoustic solitary wave (DIASW) in a multicomponent dusty plasma with adiabatic ions, superthermal electrons, and stationary dust. The reductive perturbation method is employed to derive the damped Korteweg-de Vries (DKdV) equation which describes DIASW. The result reveals that the adiabaticity of ions significantly modifies the basic features of the DIASW. The ionization effect makes the solitary wave grow, while collisions reduce the growth rate and even lead to the damping. With the increases in ionization cross section $\mathrm{\Delta }\sigma /{\sigma }_0$, ion-to-electron density ratio ${\delta }_{\mathrm{i}\mathrm{e}}$ and superthermal electrons parameter $\kappa$, the effect of ionization on DIASW enhances.

Select

Tunable energy spectrum betatron x-ray sources in a plasma wakefield Chuan-Yi Xi(奚传易), Yin-Ren Shou(寿寅任), Li-Qi Han(韩立琦), Abdughupur Ablimit(阿卜杜伍普尔·阿布力米提), Xiao-Dan Liu(刘晓丹), Yan-Ying Zhao(赵研英), and Jin-Qing Yu(余金清) Chin. Phys. B, 2024, 33 (8):  085202.  DOI: 10.1088/1674-1056/ad4531 Abstract ( 150 )   HTML ( 0 )   PDF (1323KB) ( 76 )   X-ray sources with tunable energy spectra have a wide range of applications in different scenarios due to their different penetration depths. However, existing x-ray sources face difficulties in terms of energy regulation. In this paper, we present a scheme for tuning the energy spectrum of a betatron x-ray generated from a relativistic electron bunch oscillating in a plasma wakefield. The center energy of the x-ray source can be tuned from several keV to several hundred keV by changing the plasma density, thereby extending the control range by an order of magnitude. At different central energies, the brightness of the betatron radiation is in the range of $3.7\times {10}^{22}$ to $5.5\times {10}^{22}$ photons/(0.1%BW$\cdot$s$\cdot$mm${}^2\cdot$mrad${}^2$) and the photon divergence angle is about 2 mrad. This high-brightness, energy-controlled betatron source could pave the way to a wide range of applications requiring photons of specific energy, such as phase-contrast imaging in medicine, non-destructive testing and material analysis in industry, and imaging in nuclear physics.

Select

Quasi-three-dimensional hydrodynamics of the corona region of laser irradiation of a slab Xiao-Mei Dong(董晓梅), Ben-Jin Guan(关本金), and Ying-Jun Li(李英骏) Chin. Phys. B, 2024, 33 (8):  085203.  DOI: 10.1088/1674-1056/ad4532 Abstract ( 129 )   HTML ( 1 )   PDF (2010KB) ( 98 )   This paper introduces and establishes a quasi-three-dimensional physical model of the interaction between a laser and a slab target. In contrast to previous one-dimensional analytical models, this paper innovatively fits the real laser conditions based on an isothermal, homogeneous expansion similarity solution of the ideal hydrodynamic equations. Using this simple model, the evolution law and analytical formulae for key parameters (e.g., temperature, density and scale length) in the corona region under certain conditions are given. The analytical solutions agree well with the relevant results of computational hydrodynamics simulation. For constant laser irradiation, the analytical solutions provide a meaningful power-law scaling relationship. The model provides a set of mathematical and physical tools that give theoretical support for adjusting parameters in experiments.

Select

Spectral characteristics of laser-plasma instabilities with a broadband laser Guo-Xiao Xu(许国潇), Ning Kang(康宁), An-Le Lei(雷安乐), Hui-Ya Liu(刘会亚), Yao Zhao(赵耀), Shen-Lei Zhou(周申蕾), Hong-Hai An(安红海), Jun Xiong(熊俊), Rui-Rong Wang(王瑞荣), Zhi-Yong Xie(谢志勇), Xi-Chen Zhou(周熙晨), Zhi-Heng Fang(方智恒), and Wei Wang(王伟) Chin. Phys. B, 2024, 33 (8):  085204.  DOI: 10.1088/1674-1056/ad426d Abstract ( 147 )   HTML ( 3 )   PDF (1084KB) ( 76 )   Recent experimental progresses regarding broadband laser-plasma instabilities (LPIs) show that a 0.6% laser bandwidth can reduce backscatters of the stimulated Brillouin scattering (SBS) and the stimulated Raman scattering (SRS) at normal incidence [Phys. Rev. Lett. 132 035102 (2024)]. In this paper, we present a further discussion of the spectral distributions of the scatters developed by broadband LPIs, in addition to a brief validation of the effectiveness of bandwidth on LPIs mitigation at oblique incidence. SBS backscatter has a small redshift in the broadband case contrary to the blueshift with narrowband laser, which may be explained by the self-cross beam energy transfer between the various frequency components within the bandwidth. SRS backscatter spectrum presents a peak at a longer wavelength in the broadband case compared to the short one in the narrowband case, which is possibly attributed to the mitigation effect of bandwidth on filaments at underdense plasmas. The three-halves harmonic emission (3$\omega /2$) has a one-peak spectral distribution under the broadband condition, which is different from the two-peak distribution under the narrowband condition, and may be related to the spectral mixing of different frequency components within the bandwidth if the main sources of the two are both two-plasmon decays.

Select

Calculation and prediction of divertor detachment via impurity seeding by using one-dimensional model Wen-Jie Zhou(周文杰), Xiao-Ju Liu(刘晓菊), Xiao-He Wu(邬潇河), Bang Li(李邦), Qi-Qi Shi(石奇奇), Hao-Chen Fan(樊皓尘), Yan-Jie Yang(杨艳杰), and Guo-Qiang Li(李国强) Chin. Phys. B, 2024, 33 (8):  085205.  DOI: 10.1088/1674-1056/ad426a Abstract ( 144 )   HTML ( 2 )   PDF (1047KB) ( 215 )   Achieving the detachment of divertor can help to alleviate excessive heat load and sputtering problems on the target plates, thereby extending the lifetime of divertor components for fusion devices. In order to provide a fast but relatively reliable prediction of plasma parameters along the flux tube for future device design, a one-dimensional (1D) modeling code for the operating point of impurity seeded detached divertor is developed based on Python language, which is a fluid model based on previous work (Plasma Phys. Control. Fusion 58 045013 (2016)). The experimental observation of the onset of divertor detachment by neon (Ne) and argon (Ar) seeding in EAST is well reproduced by using the 1D modeling code. The comparison between the 1D modeling and two-dimensional (2D) simulation by the SOLPS-ITER code for CFETR detachment operation with Ne and Ar seeding also shows that they are in good agreement. We also predict the radiative power loss and corresponding impurity concentration requirement for achieving divertor detachment via different impurity seeding under high heating power conditions in EAST and CFETR phase II by using the 1D model. Based on the predictions, the optimized parameter space for divertor detachment operation on EAST and CFETR is also determined. Such a simple but reliable 1D model can provide a reasonable parameter input for a detailed and accurate analysis by 2D or three-dimensional (3D) modeling tools through rapid parameter scanning.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

Select

Performance optimization of the neutron-sensitive image intensifier used in neutron imaging Jinhao Tan(谭金昊), Yushou Song(宋玉收), Jianrong Zhou(周健荣), Wenqin Yang(杨文钦), Xingfen Jiang(蒋兴奋), Jie Liu(刘杰), Chaoyue Zhang(张超月), Xiaojuan Zhou(周晓娟), Yuanguang Xia(夏远光), Shulin Liu(刘术林), Baojun Yan(闫保军), Hui Liu(刘辉), Songlin Wang(王松林), Yubin Zhao(赵豫斌), Jian Zhuang(庄建), Zhijia Sun(孙志嘉), and Yuanbo Chen(陈元柏) Chin. Phys. B, 2024, 33 (8):  086102.  DOI: 10.1088/1674-1056/ad47ad Abstract ( 145 )   HTML ( 3 )   PDF (1411KB) ( 58 )   As a non-destructive testing technology, neutron imaging plays an important role in various fields, including material science, nuclear engineering, and fundamental science. An imaging detector with a neutron-sensitive image intensifier has been developed and demonstrated to achieve good spatial resolution and timing resolution. However, the influence of the working voltage on the performance of the neutron-sensitive imaging intensifier has not been studied. To optimize the performance of the neutron-sensitive image intensifier at different voltages, experiments have been performed at the China Spallation Neutron Source (CSNS) neutron beamline. The change in the light yield and imaging quality with different voltages has been acquired. It is shown that the image quality benefits from the high gain of the microchannel plate (MCP) and the high accelerating electric field between the MCP and the screen. Increasing the accelerating electric field is more effective than increasing the gain of MCPs for the improvement of the imaging quality. Increasing the total gain of the MCP stack can be realized more effectively by improving the gain of the standard MCP than that of the nMCP. These results offer a development direction for image intensifiers in the future.

Select

Effect of interlayer bonded bilayer graphene on friction Yao-Long Li(李耀隆), Zhen-Guo Tian(田振国), Hai-Feng Yin(尹海峰), and Ren-Liang Zhang(张任良) Chin. Phys. B, 2024, 33 (8):  086103.  DOI: 10.1088/1674-1056/ad531e Abstract ( 99 )   HTML ( 0 )   PDF (1016KB) ( 31 )   We study the friction properties of interlayer bonded bilayer graphene by simulating the movement of a slider on the surface of bilayer graphene using molecular dynamics. The results show that the presence of the interlayer covalent bonds due to the local sp${}^3$ hybridization of carbon atoms in the bilayer graphene seriously reduces the frictional coefficient of the bilayer graphene surface to 30%, depending on the coverage of interlayer sp${}^3$ bonds and normal loads. For a certain coverage of interlayer sp${}^3$ bonds, when the normal load of the slider reaches a certain value, the surface of this interlayer bonded bilayer graphene will lose the friction reduction effect on the slider. Our findings provide guidance for the regulation and manipulation of the frictional properties of bilayer graphene surfaces through interlayer covalent bonds, which may be useful for applications of friction related graphene based nanodevices.

Select

Step-edge-guided nucleation and growth mode transition of α-Ga2O3 heteroepitaxy on vicinal sapphire Jinggang Hao(郝景刚), Yanfang Zhang(张彦芳), Yijun Zhang(张贻俊), Ke Xu(徐科), Genquan Han(韩根全), and Jiandong Ye(叶建东) Chin. Phys. B, 2024, 33 (8):  086104.  DOI: 10.1088/1674-1056/ad4ff6 Abstract ( 154 )   HTML ( 0 )   PDF (1777KB) ( 159 )   Controlling the epitaxial growth mode of semiconductor layers is crucial for optimizing material properties and device performance. In this work, the growth mode of $\alpha$-Ga${}_2$O${}_3$ heteroepitaxial layers was modulated by tuning miscut angles ($\theta )$ from 0${}^{\circ }$ to 7${}^{\circ }$ off the (10$\overline{1}$0) direction of sapphire (0002) substrate. On flat sapphire surfaces, the growth undergoes a typical three-dimensional (3D) growth mode due to the random nucleation on wide substrate terraces, as evidenced by the hillock morphology and high dislocation densities. As the miscut angle increases to $\theta =5^{\circ }$, the terrace width of sapphire substrate is comparable to the distance between neighboring nuclei, and consequently, the nucleation is guided by terrace edges, which energetically facilitates the growth mode transition into the desirable two-dimensional (2D) coherent growth. Consequently, the mean surface roughness decreases to only 0.62 nm, accompanied by a significant reduction in screw and edge dislocations to 0.16$\times {10}^7$ cm${}^{-2}$ and 3.58$\times {10}^9$ cm${}^{-2}$, respectively. However, the further increment of miscut angles to $\theta =7^{\circ }$ shrink the terrace width less than nucleation distance, and the step-bunching growth mode is dominant. In this circumstance, the misfit strain is released in the initial growth stage, resulting in surface morphology degradation and increased dislocation densities.

Select

Quasi-plastic deformation mechanisms and inverse Hall-Petch relationship in nanocrystalline boron carbide under compression Zhen Yue(岳珍), Jun Li(李君), Lisheng Liu(刘立胜), and Hai Mei(梅海) Chin. Phys. B, 2024, 33 (8):  086105.  DOI: 10.1088/1674-1056/ad4989 Abstract ( 132 )   HTML ( 0 )   PDF (4104KB) ( 28 )   Grain boundaries (GBs) play a significant role in the deformation behaviors of nanocrystalline ceramics. Here, we investigate the compression behaviors of nanocrystalline boron carbide (nB${}_4$C) with varying grain sizes using molecular dynamics simulations with a machine-learning force field. The results reveal quasi-plastic deformation mechanisms in nB${}_4$C: GB sliding, intergranular amorphization and intragranular amorphization. GB sliding arises from the presence of soft GBs, leading to intergranular amorphization. Intragranular amorphization arises from the interaction between grains with unfavorable orientations and the softened amorphous GBs, and finally causes structural failure. Furthermore, nB${}_4$C models with varying grain sizes from 4.07 nm to 10.86 nm display an inverse Hall-Petch relationship due to the GB sliding mechanism. A higher strain rate in nB${}_4$C often leads to a higher yield strength, following a $2/3$ power relationship. These deformation mechanisms are critical for the design of ceramics with superior mechanical properties.

Select

First-principles study on stability and superconductivity of ternary hydride LaYHx (x =2, 3, 6 and 8) Xiao-Zhen Yan(颜小珍), Xing-Zi Zhou(周幸姿), Chao-Fei Liu(刘超飞), Yin-Li Xu(徐寅力), Yi-Bin Huang(黄毅斌), Xiao-Wei Sheng(盛晓伟), and Yang-Mei Chen(陈杨梅) Chin. Phys. B, 2024, 33 (8):  086301.  DOI: 10.1088/1674-1056/ad41b8 Abstract ( 156 )   HTML ( 0 )   PDF (1825KB) ( 262 )   Recent studies have shown that the La- and Y-hydrides can exhibit significant superconducting properties under high pressures. In this paper, we investigate the stability, electronic and superconducting properties of LaYH${}_x$ ($x=2$, 3, 6 and 8) under 0-200 GPa. It is found that LaYH${}_2$ stabilizes in the $C2/m$ phase at ambient pressure, and transforms to the $Pmmn$ phase at 67 GPa. LaYH${}_3$ stabilizes in the $C2/m$ phase at ambient pressure, and undergoes phase transitions of $C2/m\to P{2}_1/m\to R3m$ at 12 GPa and 87 GPa, respectively. LaYH${}_6$ stabilizes in the $P{4}_3{2}_{1}2$ phase at ambient pressure, and undergoes phase transitions of $P{4}_3{2}_{1}2\to P4/mmm\to Cmcm$ at 28 GPa and 79 GPa, respectively. LaYH${}_8$ stabilizes in the $Imma$ phase at 60 GPa and transforms to the $P4/mmm$ phase at 117 GPa. Calculations of the electronic band structures show that the $P4/mmm$-LaYH${}_8$ and all phases of LaYH${}_2$ and LaYH${}_3$ exhibit metallic character. For the metallic phases, we then study their superconducting properties. The calculated superconducting transition temperatures ($T_{\mathrm{c}}$) are 0.47 K for $C2/m$-LaYH${}_2$ at 0 GPa, 0 K for $C2/m$-LaYH${}_3$ at 0 GPa, and 55.51 K for $P4/mmm$-LaYH${}_8$ at 50 GPa.

Select

Surface evolution of thermoelectric material KCu4Se3 explored by scanning tunneling microscopy Yumin Xia(夏玉敏), Ni Ma(马妮), Desheng Cai(蔡德胜), Yuzhou Liu(刘宇舟), Yitong Gu(谷易通), Gan Yu(于淦), Siyu Huo(霍思宇), Wenhui Pang(庞文慧), Chong Xiao(肖翀), and Shengyong Qin(秦胜勇) Chin. Phys. B, 2024, 33 (8):  086804.  DOI: 10.1088/1674-1056/ad50c4 Abstract ( 137 )   HTML ( 0 )   PDF (1462KB) ( 75 )   Novel two-dimensional thermoelectric materials have attracted significant attention in the field of thermoelectric due to their low lattice thermal conductivity. A comprehensive understanding of their microscopic structures is crucial for driving further the optimization of materials properties and developing novel functional materials. Here, by using in situ scanning tunneling microscopy, we report the atomic layer evolution and surface reconstruction on the cleaved thermoelectric material KCu${}_4$Se${}_3$ for the first time. We clearly revealed each atomic layer, including the naturally cleaved K atomic layer, the intermediate Se${}^{2-}$ atomic layer, and the Se${}^{-}$ atomic layer that emerges in the thermodynamic-stable state. Departing from the majority of studies that predominantly concentrate on macroscopic measurements of the charge transport, our results reveal the coexistence of potassium disorder and complex reconstructed patterns of selenium, which potentially influences charge carrier and lattice dynamics. These results provide direct insight into the surface microstructures and evolution of KCu${}_4$Se${}_3$, and shed useful light on designing functional materials with superior performance.

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

Select

Multi-objective global optimization approach predicted quasi-layered ternary TiOS crystals with promising photocatalytic properties Yi-Jie Xiang(向依婕), Siyan Gao(高思妍), Chunlei Wang(王春雷), Haiping Fang(方海平), Xiangmei Duan(段香梅), Yi-Feng Zheng(郑益峰), and Yue-Yu Zhang(张越宇) Chin. Phys. B, 2024, 33 (8):  087101.  DOI: 10.1088/1674-1056/ad4bc3 Abstract ( 190 )   HTML ( 2 )   PDF (1438KB) ( 49 )   Titanium dioxide (TiO${}_2$) has attracted considerable research attentions for its promising applications in solar cells and photocatalytic devices. However, the intrinsic challenge lies in the relatively low energy conversion efficiency of TiO${}_2$, primarily attributed to the substantial band gaps (exceeding 3.0 eV) associated with its rutile and anatase phases. Leveraging multi-objective global optimization, we have identified two quasi-layered ternary Ti-O-S crystals, composed of titanium, oxygen, and sulfur. The calculations of formation energy, phonon dispersions, and thermal stability confirm the chemical, dynamical and thermal stability of these newly discovered phases. Employing the state-of-art hybrid density functional approach and many-body perturbation theory (quasiparticle GW approach and Bethe-Salpeter equation), we calculate the optical properties of both the TiOS phases. Significantly, both phases show favorable photocatalytic characteristics, featuring band gaps suitable for visible optical absorption and appropriate band alignments with water for effective charge carrier separation. Therefore, ternary compound TiOS holds the potential for achieving high-efficiency photochemical conversion, showing our multi-objective global optimization provides a new approach for novel environmental and energy materials design with multicomponent compounds.

Select

Topological phase transition in compressed van der Waals superlattice heterostructure BiTeCl/HfTe2 Zhilei Li(李志磊), Yinxiang Li(李殷翔), Yiting Wang(王奕婷), Wenzhi Chen(陈文执), and Bin Chen(陈斌) Chin. Phys. B, 2024, 33 (8):  087102.  DOI: 10.1088/1674-1056/ad462e Abstract ( 124 )   HTML ( 0 )   PDF (2337KB) ( 34 )   Based on first-principles calculations, we investigate the electronic band structures and topological properties of heterostructure BiTeCl/HfTe${}_2$ under $c$-direction strain. In the primitive structure, this material undergoes a phase transition from an insulator with a narrow indirect gap to a metal by strong spin-orbital coupling. When strain effect is considered, band inversion at time-reversal invariant point $Z$ is responsible for the topological phase transition. These nontrivial topologies are caused by two different types of band crossings. The observable topological surface states in (110) surface also support that this material experiences topological phase transition twice. The layered heterostructure with van der Waals force provides us with a new desirable platform upon which to control topological phase transition and construct topological superconductors.

Select

Effect of Lewis acid-base additive on lead-free Cs2SnI6 thin film prepared by direct solution coating process Saqib Nawaz Khan, Yan Wang(王燕), Lixiang Zhong(钟李祥), Huili Liang(梁会力), Xiaolong Du(杜小龙), and Zengxia Mei(梅增霞) Chin. Phys. B, 2024, 33 (8):  087201.  DOI: 10.1088/1674-1056/ad4a39 Abstract ( 130 )   HTML ( 1 )   PDF (1681KB) ( 111 )   Inorganic Cs${}_2$SnI${}_6$ perovskite has exhibited substantial potential for light harvesting due to its exceptional optoelectronic properties and remarkable stability in ambient conditions. The charge transport characteristics within perovskite films are subject to modulation by various factors, including crystalline orientation, morphology, and crystalline quality. Achieving preferred crystalline orientation and film morphology via a solution-based process is challenging for Cs${}_2$SnI${}_6$ films. In this work, we employed thiourea as an additive to optimize crystal orientation, enhance film morphology, promote crystallization, and achieve phase purity. Thiourea lowers the surface energy of the (222) plane along the $⟨111⟩$ direction, confirmed by x-ray diffraction, x-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy studies, and density functional theory calculations. Varying thiourea concentration enables a bandgap tuning of Cs${}_2$SnI${}_6$ from 1.52 eV to 1.07 eV. This approach provides a novel method for utilizing Cs${}_2$SnI${}_6$ films in high-performance optoelectronic devices.

Select

Topological superconductors with spin-triplet pairings and Majorana Fermi arcs Shi Huang(黄石) and Xi Luo(罗熙) Chin. Phys. B, 2024, 33 (8):  087301.  DOI: 10.1088/1674-1056/ad462f Abstract ( 103 )   HTML ( 0 )   PDF (1789KB) ( 31 )   We construct a three-dimensional topological superconductor Bogoliubov-de Gennes (BdG) Hamiltonian with the normal state being a three-dimensional topological insulator. By introducing inter-orbital spin-triplet pairings term ${\Delta }_3$, there are topological Majorana nodes in the bulk and they are connected by Majorana Fermi arcs on the surface, similar to the case of Weyl semimetal. Furthermore, by adding an inversion-breaking term to the normal state, momentum-independent pairing terms with different parities can coexist in the BdG Hamiltonian, which creates more Majorana modes similar to Andreev bound states and a richer phase diagram.

Select

GaInX3 (X = S, Se, Te): Ultra-low thermal conductivity and excellent thermoelectric performance Zhi-Fu Duan(段志福), Chang-Hao Ding(丁长浩), Zhong-Ke Ding(丁中科), Wei-Hua Xiao(肖威华), Fang Xie(谢芳), Nan-Nan Luo(罗南南), Jiang Zeng(曾犟), Li-Ming Tang(唐黎明), and Ke-Qiu Chen(陈克求) Chin. Phys. B, 2024, 33 (8):  087302.  DOI: 10.1088/1674-1056/ad47e3 Abstract ( 152 )   HTML ( 0 )   PDF (1951KB) ( 204 )   Seeking intrinsically low thermal conductivity materials is a viable strategy in the pursuit of high-performance thermoelectric materials. Here, by using first-principles calculations and semiclassical Boltzmann transport theory, we systemically investigate the carrier transport and thermoelectric properties of monolayer Janus GaIn$X_3$ ($X=\mathrm{S}$, Se, Te). It is found that the lattice thermal conductivities can reach values as low as 3.07 W$\cdot$m${}^{-1}\cdot$K${}^{-1}$, 1.16 W$\cdot$m${}^{-1}\cdot$K${}^{-1}$ and 0.57 W$\cdot$m${}^{-1}\cdot$K${}^{-1}$ for GaInS${}_3$, GaInSe${}_3$, and GaInTe${}_3$, respectively, at room temperature. This notably low thermal conductivity is attributed to strong acoustic-optical phonon coupling caused by the presence of low-frequency optical phonons in GaIn$X_3$ materials. Furthermore, by integrating the characteristics of electronic and thermal transport, the dimensionless figure of merit $ZT$ can reach maximum values of 0.95, 2.37, and 3.00 for GaInS${}_3$, GaInSe${}_3$, and GaInTe${}_3$, respectively. Our results suggest that monolayer Janus GaIn$X_3$ ($X=\mathrm{S}$, Se, Te) is a promising candidate for thermoelectric and heat management applications.

Select

Experimental observation of Fermi-level flat band in novel kagome metal CeNi5 Xue-Zhi Chen(陈学智), Le Wang(王乐), Shuai Zhang(张帅), Ren-Jie Zhang(张任杰), Yi-Wei Cheng(程以伟), Yu-Dong Hu(胡裕栋), Cheng-Nuo Meng(孟承诺), Zheng-Tai Liu(刘正太), Bai-Qing Lv(吕佰晴), and Yao-Bo Huang(黄耀波) Chin. Phys. B, 2024, 33 (8):  087402.  DOI: 10.1088/1674-1056/ad4019 Abstract ( 146 )   HTML ( 0 )   PDF (2435KB) ( 124 )   Kagome materials are a class of material with a lattice structure composed of corner-sharing triangles that produce various exotic electronic phenomena, such as Dirac fermions, van Hove singularities, and flat bands. However, most of the known kagome materials have a flat band detached from the Fermi energy, which limits the investigation of the emergent flat band physics. In this work, by combining soft x-ray angle-resolved photoemission spectroscopy (ARPES) and the first-principles calculations, the electronic structure is investigated of a novel kagome metal CeNi${}_5$ with a clear dispersion along the $k_z$ direction and a Fermi level flat band in the $\Gamma$-$K$-$M$-$\Gamma$ plane. Besides, resonant ARPES experimental results indicate that the valence state of Ce ions is close to 4${}^{+}$, which is consistent with the transport measurement result. Our results demonstrate the unique electronic properties of CeNi${}_5$ as a new kagome metal and provide an ideal platform for exploring the flat band physics and the interactions between different types of flat bands by tuning the valence state of Ce ions.

Select

Control of interfacial reaction and defect formation in Gd/Bi2Te2.7Se0.3 composites with excellent thermoelectric and magnetocaloric properties Tianchang Xue(薛天畅), Ping Wei(魏平), Chengshan Liu(刘承姗), Longzhou Li(李龙舟), Wanting Zhu(朱婉婷), Xiaolei Nie(聂晓蕾), and Wenyu Zhao(赵文俞) Chin. Phys. B, 2024, 33 (8):  087403.  DOI: 10.1088/1674-1056/ad4cd3 Abstract ( 126 )   HTML ( 0 )   PDF (1556KB) ( 45 )   The method to combine thermoelectric (TE) and magnetocaloric (MC) cooling techniques lies in developing a new material that simultaneously possesses a large TE and good MC cooling performance. In this work, using n-type Bi${}_2$Te${}_{2.7}$Se${}_{0.3}$ (BTS) as the TE base material and Gd as the second-phase MC material, Gd/BTS composites were prepared by the spark plasma sintering method. In the composites, interfacial reaction between Gd and BTS was identified, resulting in the formation of GdTe, which has a large impact on the electron concentration through the adjustment of defect concentration. The MC/TE composite containing 2.5 wt% Gd exhibited a $ZT$ value of 0.6 at 300 K, essentially retaining the original TE performance, while all the composites largely maintained the excellent MC performance of Gd. This work provides a potential pathway to achieving high performance in MC/TE composites.

Select

Half-integer Shapiro steps in MgB2 focused He ion beam Josephson junctions Dali Yin(殷大利), Xinwei Cai(蔡欣炜), Tiequan Xu(徐铁权), Ruining Sun(孙瑞宁), Ying Han(韩颖), Yan Zhang(张焱), Yue Wang(王越), and Zizhao Gan(甘子钊) Chin. Phys. B, 2024, 33 (8):  087404.  DOI: 10.1088/1674-1056/ad4d62 Abstract ( 167 )   HTML ( 3 )   PDF (3051KB) ( 69 )   Half-integer microwave induced steps (Shapiro steps) have been observed in many different Josephson junction systems, which have attracted a lot of attention because they signify the deviation of current phase relation (CPR) and uncover many unconventional physical properties. In this article, we first report the discovery of half-integer Shapiro steps in MgB${}_2$ focused He ion beam (He-FIB) Josephson junctions. The half-integer steps' dependence on microwave frequency, temperature, microwave power, and magnetic field is also analyzed. We find that the existence of half-integer steps can be controlled by the magnetic field periodically, which is similar to that of high temperature superconductor (HTS) grain boundary junctions, and the similarity of the microstructures between gain boundary junctions and He-FIB junctions is discussed. As a consequence, we mainly attribute the physical origin of half-integer steps in MgB${}_2$ He-FIB junctions to the model that a He-FIB junction is analogous to a parallel junctions' array. Our results show that He-FIB technology is a promising platform for researching CPR in junctions made of different superconductors.

Select

Evolution of anomalous Hall effect in ferromagnetic Weyl semimetal NbxZr1-xCo2Sn Bo-Wen Chen(陈博文) and Bing Shen(沈冰) Chin. Phys. B, 2024, 33 (8):  087501.  DOI: 10.1088/1674-1056/ad4a3b Abstract ( 152 )   HTML ( 4 )   PDF (1105KB) ( 207 )   Magnetic topological semimetal can host various topological non-trivial states leading to exotic novel transport properties. Here we report the systematic magneto-transport studies on the Heusler alloy Nb${}_x$Zr${}_{1-x}$Co${}_2$Sn considered as a ferromagnetic (FM) Weyl semimetal. The cusp anomaly of temperature-dependent resistivity and large isotropic negative magneto-resistivity (MR) emerge around the FM transition consistent with the theoretical half-metallic predictions. The prominent anomalous Hall effect (AHE) has the same behavior with the applied field along various crystal directions. The Nb doping introduces more disorder resulting in the enhancement of the upturn for the temperature-dependent resistivity in low temperatures. With Nb doping, the AHE exhibits systemic evolution with the Fermi level lifted. At the doping level of $x=0.25$, the AHE mainly originates from the intrinsic contribution related to non-trivial topological Weyl states.

Select

First-principles study of electronic and magnetic properties of Fe atoms on Cu2N/Cu(100) Jiale Chen(陈佳乐) and Jun Hu(胡军) Chin. Phys. B, 2024, 33 (8):  087502.  DOI: 10.1088/1674-1056/ad5275 Abstract ( 134 )   HTML ( 4 )   PDF (1102KB) ( 94 )   First-principles calculations were conducted to investigate the structural, electronic, and magnetic properties of single Fe atoms and Fe dimers on Cu${}_2$N/Cu(100). Upon adsorption of an Fe atom onto Cu${}_2$N/Cu(100), robust Fe-N bonds form, resulting in the incorporation of both single Fe atoms and Fe dimers within the surface Cu${}_2$N layer. The partial occupancy of Fe-3d orbitals lead to large spin moments on the Fe atoms. Interestingly, both single Fe atoms and Fe dimers exhibit in-plane magnetic anisotropy, with the magnetic anisotropy energy (MAE) of an Fe dimer exceeding twice that of a single Fe atom. This magnetic anisotropy can be attributed to the predominant contribution of the component along the $x$ direction of the spin-orbital coupling Hamiltonian. Additionally, the formation of Fe-Cu dimers may further boost the magnetic anisotropy, as the energy levels of the Fe-3d orbitals are remarkably influenced by the presence of Cu atoms. Our study manifests the significance of uncovering the origin of magnetic anisotropy in engineering the magnetic properties of magnetic nanostructures.

Select

Frequency combs based on magnon-skyrmion interaction in magnetic nanotubes Tijjani Abdulrazak, Xuejuan Liu(刘雪娟), Zhejunyu Jin(金哲珺雨), Yunshan Cao(曹云姗), and Peng Yan(严鹏) Chin. Phys. B, 2024, 33 (8):  087503.  DOI: 10.1088/1674-1056/ad4ff5 Abstract ( 140 )   HTML ( 0 )   PDF (739KB) ( 73 )   Within the magnonics community, there has been a lot of interests in the magnon-skyrmion interaction. Magnons and skyrmions are two intriguing phenomena in condensed matter physics, and magnetic nanotubes have emerged as a suitable platform to study their complex interactions. We show that magnon frequency combs can be induced in magnetic nanotubes by three-wave mixing between the propagating magnons and skyrmion. This study enriches our fundamental comprehension of magnon-skyrmion interactions and holds promise for developing innovative spintronic devices and applications. This frequency comb tunability and unique spectral features offer a rich platform for exploring novel avenues in magnetic nanotechnology.

Select

Magnetic domain structures in ultrathin Bi2Te3/CrTe2 heterostructures Tirui Xia(夏体瑞), Xiaotian Yang(杨笑天), Yifan Zhang(张逸凡), Xinqi Liu(刘馨琪), Xinyu Cai(蔡新雨), Chang Liu(刘畅), Qi Yao(姚岐), Xufeng Kou(寇煦丰), and Wenbo Wang(王文波) Chin. Phys. B, 2024, 33 (8):  087504.  DOI: 10.1088/1674-1056/ad4a3a Abstract ( 231 )   HTML ( 5 )   PDF (2896KB) ( 141 )   Chromium tellurium compounds are important two-dimensional van der Waals ferromagnetic materials with high Curie temperature and chemical stability in air, which is promising for applications in spintronic devices. Here, high-quality spin-orbital-torque (SOT) device, Bi${}_2$Te${}_3$/CrTe${}_2$ heterostructure was epitaxially grown on Al${}_2$O${}_3$ (0001) substrates. Anomalous Hall measurements indicate the existence of strong ferromagnetism in this device with the CrTe${}_2$ thickness down to 10 nm. In order to investigate its micromagnetic structure, cryogenic magnetic force microscope (MFM) was utilized to measure the magnetic domain evolutions at various temperatures and magnetic fields. The virgin domain state of the device shows a worm-like magnetic domain structure with the size around 0.6 μm-0.8 μm. Larger irregular-shape magnetic domains (>1 μm) can be induced and pinned, after the field is increased to coercive field and ramped back to low fields. The temperature-dependent MFM signals exhibit a nice mean-field-like ferromagnetic transition with Curie temperature around 201.5 K, indicating a robust ferromagnetic ordering. Such a device can be potentially implemented in future magnetic memory technology.

Select

Dielectric anisotropy in liquid crystal mixtures with nematic and smectic phases Xing-Zhou Tang(汤星舟), Jia-Yao Ye(叶家耀), Zi-Ye Wang(王子烨), Hao-Yi Jiang(姜皓译), Xiao-Hu Shang(尚小虎), Zhao-Yan Yang(杨朝雁), and Bing-Xiang Li(李炳祥) Chin. Phys. B, 2024, 33 (8):  087702.  DOI: 10.1088/1674-1056/ad4cd7 Abstract ( 208 )   HTML ( 1 )   PDF (1253KB) ( 229 )   The modulation of dielectric anisotropy ($\mathrm{\Delta }\epsilon$) is pivotal for elucidating molecular interactions and directing the alignment of liquid crystals. In this study, we combine liquid crystals with opposing dielectric anisotropies to explore the impact of varying concentrations on their properties. We report the sign-reversal of $\mathrm{\Delta }\epsilon$ in both the nematic and smectic A phases of these mixed liquid crystals, alongside a dual-frequency behaviour across a broad temperature spectrum. Our research further quantifies the influence of mixture ratios under various temperatures and electric field frequencies. This exploration may pave the way for the discovery of new physical phenomena.

Select

Quantitative analysis of laser-generated ultrasonic wave characteristics and their correlation with grain size in polycrystalline materials Zhaowen Xu(徐兆文), Xue Bai(白雪), Jian Ma(马健), Zhuangzhuang Wan(万壮壮), and Chaoqun Wang(王超群) Chin. Phys. B, 2024, 33 (8):  087801.  DOI: 10.1088/1674-1056/ad50bd Abstract ( 147 )   HTML ( 0 )   PDF (3838KB) ( 45 )   Quantitative relationship between nanosecond pulsed laser parameters and the characteristics of laser-generated ultrasonic waves in polycrystalline materials was evaluated. The high energy of the pulsed laser with a large irradiation spot simultaneously generated ultrasonic longitudinal and shear waves at the epicenter under the slight ablation regime. An optimized denoising technique based on wavelet thresholding and variational mode decomposition was applied to reduce noise in shear waves with a low signal-to-noise ratio. An approach for characterizing grain size was proposed using spectral central frequency ratio (SCFR) based on time-frequency analysis. The results demonstrate that the generation regime of ultrasonic waves is not solely determined by the laser power density; even at high power densities, a high energy with a large spot can generate an ultrasonic waveform dominated by the thermoelastic effect. This is ascribed to the intensification of the thermoelastic effect with the proportional increase in laser irradiation spot area for a given laser power density. Furthermore, both longitudinal and shear wave SCFRs are linearly related to grain size in polycrystalline materials; however, the shear wave SCFR is more sensitive to finer-grained materials. This study holds great significance for evaluating metal material properties using laser ultrasound.

INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY

Select

Single crystal growth and transport properties of narrow-bandgap semiconductor RhP2 De-Sheng Wu(吴德胜), Ping Zheng(郑萍), and Jian-Lin Luo(雒建林) Chin. Phys. B, 2024, 33 (8):  088101.  DOI: 10.1088/1674-1056/ad4cd5 Abstract ( 135 )   HTML ( 0 )   PDF (2293KB) ( 67 )   We report the growth of high-quality single crystals of RhP${}_2$, and systematically study its structure and physical properties by transport, magnetism, and heat capacity measurements. Single-crystal x-ray diffraction reveals that RhP${}_2$ adopts a monoclinic structure with the cell parameters a=5.7347(10) Å, b=5.7804(11) Å, and c=5.8222(11) Å, space group $P{2}_1/c$ (No. 14). The electrical resistivity $\rho (T)$ measurements indicate that RhP${}_2$ exhibits narrow-bandgap behavior with the activation energies of 223.1 meV and 27.4 meV for two distinct regions, respectively. The temperature-dependent Hall effect measurements show electron domain transport behavior with a low charge carrier concentration. We find that RhP${}_2$ has a high mobility ${\mu }_{\mathrm{e}}\sim 210$ cm${}^2$$\cdot$V${}^{-1}$$\cdot$s${}^{-1}$ with carrier concentrations $n_{\mathrm{e}}\sim 3.3\times {10}^{18}$ cm${}^{-3}$ at 300 K with a narrow-bandgap feature. The high mobility ${\mu }_{\mathrm{e}}$ reaches the maximum of approximately 340 cm${}^2$$\cdot$V${}^{-1}$$\cdot$s${}^{-1}$ with carrier concentrations $n_{\mathrm{e}}\sim 2\times {10}^{18}$ cm${}^{-3}$ at 100 K. No magnetic phase transitions are observed from the susceptibility $\chi (T)$ and specific heat $C_{\mathrm{p}}(T)$ measurements of RhP${}_2$. Our results not only provide effective potential as a material platform for studying exotic physical properties and electron band structures but also motivate further exploration of their potential photovoltaic and optoelectronic applications.

Select

Defect chemistry engineering of Ga-doped garnet electrolyte with high stability for solid-state lithium metal batteries Sihan Chen(陈思汗), Jun Li(黎俊), Keke Liu(刘可可), Xiaochen Sun(孙笑晨), Jingwei Wan(万京伟), Huiyu Zhai(翟慧宇), Xinfeng Tang(唐新峰), and Gangjian Tan(谭刚健) Chin. Phys. B, 2024, 33 (8):  088203.  DOI: 10.1088/1674-1056/ad41b9 Abstract ( 108 )   HTML ( 0 )   PDF (3279KB) ( 117 )   Ga-doped Li${}_7$La${}_3$Zr${}_2$O${}_{12}$ (Ga-LLZO) has long been considered as a promising garnet-type electrolyte candidate for all-solid-state lithium metal batteries (ASSLBs) due to its high room temperature ionic conductivity. However, the typical synthesis of Ga-LLZO is usually accompanied by the formation of undesired LiGaO${}_2$ impurity phase that causes severe instability of the electrolyte in contact with molten Li metal during half/full cell assembly. In this study, we show that by simply engineering the defect chemistry of Ga-LLZO, namely, the lithium deficiency level, LiGaO${}_2$ impurity phase is effectively inhibited in the final synthetic product. Consequently, defect chemistry engineered Ga-LLZO exhibits excellent electrochemical stability against lithium metal, while its high room temperature ionic conductivity ($\sim 1.9\times {10}^{-3}$ S$\cdot$cm${}^{-1}$) is well reserved. The assembled Li/Ga-LLZO/Li symmetric cell has a superior critical current density of 0.9 mA$\cdot$cm${}^{-2}$, and cycles stably for 500 hours at a current density of 0.3 mA$\cdot$cm${}^{-2}$. This research facilitates the potential commercial applications of high performance Ga-LLZO solid electrolytes in ASSLBs.

Select

Subtraction of liposome signals in cryo-EM structural determination of protein-liposome complexes Shouqing Li(李首卿), Ming Li(李明), Yumei Wang(王玉梅), and Xueming Li(李雪明) Chin. Phys. B, 2024, 33 (8):  088702.  DOI: 10.1088/1674-1056/ad4cdb Abstract ( 178 )   HTML ( 2 )   PDF (2521KB) ( 81 )   Reconstituting membrane proteins in liposomes and determining their structure is a common method for determining membrane protein structures using single-particle cryo-electron microscopy (cryo-EM). However, the strong signal of liposomes under cryo-EM imaging conditions often interferes with the structural determination of the embedded membrane proteins. Here, we propose a liposome signal subtraction method based on single-particle two-dimensional (2D) classification average images, aimed at enhancing the reconstruction resolution of membrane proteins. We analyzed the signal distribution characteristics of liposomes and proteins within the 2D classification average images of protein-liposome complexes in the frequency domain. Based on this analysis, we designed a method to subtract the liposome signals from the original particle images. After the subtraction, the accuracy of single-particle three-dimensional (3D) alignment was improved, enhancing the resolution of the final 3D reconstruction. We demonstrated this method using a PIEZO1-proteoliposome dataset by improving the resolution of the PIEZO1 protein.

Select

Tuning the diffusion constant to optimize the readout of positional information of spatial concentration patterns Ka Kit Kong(江嘉杰), Chunxiong Luo(罗春雄), and Feng Liu(刘峰) Chin. Phys. B, 2024, 33 (8):  088703.  DOI: 10.1088/1674-1056/ad4cda Abstract ( 125 )   HTML ( 3 )   PDF (965KB) ( 59 )   Positional information encoded in spatial concentration patterns is crucial for the development of multicellular organisms. However, it is still unclear how such information is affected by the physically dissipative diffusion process. Here we study one-dimensional patterning systems with analytical derivation and numerical simulations. We find that the diffusion constant of the patterning molecules exhibits a nonmonotonic effect on the readout of the positional information from the concentration patterns. Specifically, there exists an optimal diffusion constant that maximizes the positional information. Moreover, we find that the energy dissipation due to the physical diffusion imposes a fundamental upper limit on the positional information.

Select

CRB: A new rumor blocking algorithm in online social networks based on competitive spreading model and influence maximization Chen Dong(董晨), Gui-Qiong Xu(徐桂琼), and Lei Meng(孟蕾) Chin. Phys. B, 2024, 33 (8):  088901.  DOI: 10.1088/1674-1056/ad531f Abstract ( 135 )   HTML ( 1 )   PDF (818KB) ( 82 )   The virtuality and openness of online social platforms make networks a hotbed for the rapid propagation of various rumors. In order to block the outbreak of rumor, one of the most effective containment measures is spreading positive information to counterbalance the diffusion of rumor. The spreading mechanism of rumors and effective suppression strategies are significant and challenging research issues. Firstly, in order to simulate the dissemination of multiple types of information, we propose a competitive linear threshold model with state transition (CLTST) to describe the spreading process of rumor and anti-rumor in the same network. Subsequently, we put forward a community-based rumor blocking (CRB) algorithm based on influence maximization theory in social networks. Its crucial step is to identify a set of influential seeds that propagate anti-rumor information to other nodes, which includes community detection, selection of candidate anti-rumor seeds and generation of anti-rumor seed set. Under the CLTST model, the CRB algorithm has been compared with six state-of-the-art algorithms on nine online social networks to verify the performance. Experimental results show that the proposed model can better reflect the process of rumor propagation, and review the propagation mechanism of rumor and anti-rumor in online social networks. Moreover, the proposed CRB algorithm has better performance in weakening the rumor dissemination ability, which can select anti-rumor seeds in networks more accurately and achieve better performance in influence spread, sensitivity analysis, seeds distribution and running time.

Select

Influence of network structure on spreading dynamics via tie range Min Li(李敏), Yurong Song(宋玉蓉), Bo Song(宋波), Ruqi Li(李汝琦), Guo-Ping Jiang(蒋国平), and Zhang Hui(张晖) Chin. Phys. B, 2024, 33 (8):  088902.  DOI: 10.1088/1674-1056/ad50c3 Abstract ( 133 )   HTML ( 4 )   PDF (3067KB) ( 170 )   There are various phenomena of malicious information spreading in the real society, which cause many negative impacts on the society. In order to better control the spreading, it is crucial to reveal the influence of network structure on network spreading. Motifs, as fundamental structures within a network, play a significant role in spreading. Therefore, it is of interest to investigate the influence of the structural characteristics of basic network motifs on spreading dynamics. Considering the edges of the basic network motifs in an undirected network correspond to different tie ranges, two edge removal strategies are proposed, short ties priority removal strategy and long ties priority removal strategy. The tie range represents the second shortest path length between two connected nodes. The study focuses on analyzing how the proposed strategies impact network spreading and network structure, as well as examining the influence of network structure on network spreading. Our findings indicate that the long ties priority removal strategy is most effective in controlling network spreading, especially in terms of spread range and spread velocity. In terms of network structure, the clustering coefficient and the diameter of network also have an effect on the network spreading, and the triangular structure as an important motif structure effectively inhibits the spreading.

Select

Detecting the core of a network by the centralities of the nodes Peijie Ma(马佩杰), Xuezao Ren(任学藻), Junfang Zhu(朱军芳), and Yanqun Jiang(蒋艳群) Chin. Phys. B, 2024, 33 (8):  088903.  DOI: 10.1088/1674-1056/ad4cd4 Abstract ( 116 )   HTML ( 3 )   PDF (527KB) ( 38 )   Many networks exhibit the core/periphery structure. Core/periphery structure is a type of meso-scale structure that consists of densely connected core nodes and sparsely connected peripheral nodes. Core nodes tend to be well-connected, both among themselves and to peripheral nodes, which tend not to be well-connected to other nodes. In this brief report, we propose a new method to detect the core of a network by the centrality of each node. It is discovered that such nodes with non-negative centralities often consist in the core of the networks. The simulation is carried out on different real networks. The results are checked by the objective function. The checked results may show the effectiveness of the simulation results by the centralities of the nodes on the real networks. Furthermore, we discuss the characters of networks with the single core/periphery structure and point out the scope of the application of our method at the end of this paper.