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15 October 2024, Volume 33 Issue 10 Previous issue    Next issue

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TOPICAL REVIEW — Optical field manipulation

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Light-field modulation and optimization near metal nanostructures utilizing spatial light modulators Zini Cao(曹子倪), Hai Lin(林海), Yuqing Cheng(程宇清), Yixuan Xu(徐艺轩), Qihuang Gong(龚旗煌), and Guowei Lü(吕国伟) Chin. Phys. B, 2024, 33 (10):  104201.  DOI: 10.1088/1674-1056/ad6555 Abstract ( 86 )   HTML ( 3 )   PDF (1470KB) ( 52 )   Plasmonic modes within metal nanostructures play a pivotal role in various nanophotonic applications. However, a significant challenge arises from the fixed shapes of nanostructures post-fabrication, resulting in limited modes under ordinary illumination. A promising solution lies in far-field control facilitated by spatial light modulators (SLMs), which enable on-site, real-time, and non-destructive manipulation of plasmon excitation. Through the robust modulation of the incident light using SLMs, this approach enables the generation, optimization, and dynamic control of surface plasmon polariton (SPP) and localized surface plasmon (LSP) modes. The versatility of this technique introduces a rich array of tunable degrees of freedom to plasmon-enhanced spectroscopy, offering novel approaches for signal optimization and functional expansion in this field. This paper provides a comprehensive review of the generation and modulation of SPP and LSP modes through far-field control with SLMs and highlights the diverse applications of this optical technology in plasmon-enhanced spectroscopy.

SPECIAL TOPIC — Quantum computing and quantum sensing

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On-chip quantum NOON state sensing for temperature and humidity Weihong Luo(罗伟宏), Chao Wu(吴超), Yuxing Du(杜昱星), Chang Zhao(赵畅), Miaomiao Yu(余苗苗), Pingyu Zhu(朱枰谕), Kaikai Zhang(张凯凯), and Ping Xu(徐平) Chin. Phys. B, 2024, 33 (10):  100305.  DOI: 10.1088/1674-1056/ad72e2 Abstract ( 72 )   HTML ( 0 )   PDF (1792KB) ( 92 )   A maximal photon number entangled state, namely NOON state, can be adopted for sensing with a quantum enhanced precision. In this work, we designed silicon quantum photonic chips containing two types of Mach-Zehnder interferometers wherein the two-photon NOON state, sensing element for temperature or humidity, is generated. Compared with classical light or single photon case, two-photon NOON state sensing shows a solid enhancement in the sensing resolution and precision. As the first demonstration of on-chip quantum photonic sensing, it reveals the advantages of photonic chips for high integration density, small-size, stability for multiple-parameter sensing serviceability. A higher sensing precision is expected to beat the standard quantum limit with a higher photon number NOON state.

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Vector magnetometry in zero bias magnetic field using nitrogen-vacancy ensembles Chunxing Li(李春兴), Fa-Zhan Shi(石发展), Jingwei Zhou(周经纬), and Peng-Fei Wang(王鹏飞) Chin. Phys. B, 2024, 33 (10):  100701.  DOI: 10.1088/1674-1056/ad73af Abstract ( 62 )   HTML ( 0 )   PDF (2756KB) ( 45 )   The application of the vector magnetometry based on nitrogen-vacancy (NV) ensembles has been widely investigated in multiple areas. It has the superiority of high sensitivity and high stability in ambient conditions with microscale spatial resolution. However, a bias magnetic field is necessary to fully separate the resonance lines of optically detected magnetic resonance (ODMR) spectrum of NV ensembles. This brings disturbances in samples being detected and limits the range of application. Here, we demonstrate a method of vector magnetometry in zero bias magnetic field using NV ensembles. By utilizing the anisotropy property of fluorescence excited from NV centers, we analyzed the ODMR spectrum of NV ensembles under various polarized angles of excitation laser in zero bias magnetic field with a quantitative numerical model and reconstructed the magnetic field vector. The minimum magnetic field modulus that can be resolved accurately is down to $\sim 0.64 $ G theoretically depending on the ODMR spectral line width (1.8 MHz), and $\sim 2 $ G experimentally due to noises in fluorescence signals and errors in calibration. By using $^{13}$C purified and low nitrogen concentration diamond combined with improving calibration of unknown parameters, the ODMR spectral line width can be further decreased below 0.5 MHz, corresponding to $\sim 0.18 $ G minimum resolvable magnetic field modulus.

SPECIAL TOPIC — Recent progress on kagome metals and superconductors

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Magnetoresistance hysteresis in the superconducting state of kagome CsV3Sb5 Tian Le(乐天), Jinjin Liu(刘锦锦), Zhiwei Wang(王秩伟), and Xiao Lin(林效) Chin. Phys. B, 2024, 33 (10):  107402.  DOI: 10.1088/1674-1056/ad6423 Abstract ( 78 )   HTML ( 0 )   PDF (872KB) ( 39 )   The hysteresis of magnetoresistance observed in superconductors is of great interest due to its potential connection with unconventional superconductivity. In this study, we perform electrical transport measurements on kagome superconductor CsV$_3$Sb$_5$ nanoflakes and uncover unusual hysteretic behavior of magnetoresistance in the superconducting state. This hysteresis can be induced by applying either a large DC or AC current at temperatures ($T$) well below the superconducting transition temperature ($T_{\rm c}$). As $T$ approaches $T_{\rm c}$, similar weak hysteresis is also detected by applying a small current. Various scenarios are discussed, with particular focus on the effects of vortex pinning and the presence of time-reversal-symmtery-breaking superconducting domains. Our findings support the latter, hinting at chiral superconductivity in kagome superconductors.

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Surface-sensitive electronic structure of kagome superconductor CsV3Sb5 Zhisheng Zhao(赵志生), Jianghao Yao(姚江浩), Rui Xu(徐瑞), Yuzhe Wang(王禹喆), Sen Liao(廖森), Zhengtai Liu(刘正太), Dawei Shen (沈大伟), Shengtao Cui(崔胜涛), Zhe Sun(孙喆), Yilin Wang(王义林), Donglai Feng(封东来), and Juan Jiang(姜娟) Chin. Phys. B, 2024, 33 (10):  107403.  DOI: 10.1088/1674-1056/ad7016 Abstract ( 80 )   HTML ( 1 )   PDF (2224KB) ( 34 )   We systematically study the electronic structure of a kagome superconductor ${\rm Cs}{\rm V}_{{\rm 3}}{{\rm Sb}}_{{\rm 5}}$ at different temperatures covering both its charge density wave state and normal state with angle-resolved photoemission spectroscopy. We observe that the V-shaped band around $\bar{\varGamma }$ shows three different behaviors, referred to as $\alpha /\alpha '$, $\beta $ and $\gamma $, mainly at different temperatures. Detailed investigations confirm that these bands are all from the same bulk Sb-p$_{z}$ origin, but they are quite sensitive to the sample surface conditions mainly modulated by temperature. Thus, the intriguing temperature dependent electronic behavior of the band near $\bar{\varGamma }$ is affected by the sample surface condition, rather than intrinsic electronic behavior originating from the phase transition. Our result systematically reveals the confusing electronic structure behavior of the energy bands around $\bar{\varGamma }$, facilitating further exploration of the novel properties in this material.

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Pairing correlation of the kagome-lattice Hubbard model with the nearest-neighbor interaction Chen Yang(杨晨), Chao Chen(陈超), Runyu Ma(马润宇), Ying Liang(梁颖), and Tianxing Ma(马天星) Chin. Phys. B, 2024, 33 (10):  107404.  DOI: 10.1088/1674-1056/ad7578 Abstract ( 72 )   HTML ( 4 )   PDF (927KB) ( 91 )   A recently discovered family of kagome lattice materials, ${A}\mathrm{V}_{3}\mathrm{Sb}_{5}$ (${A}=\mathrm{K,Rb,Cs}$), has attracted great interest, especially in the debate over their dominant superconducting pairing symmetry. To explore this issue, we study the superconducting pairing behavior within the kagome-lattice Hubbard model through the constrained path Monte Carlo method. It is found that doping around the Dirac point generates a dominant next-nearest-neighbor-d pairing symmetry driven by on-site Coulomb interaction $U$. However, when considering the nearest-neighbor interaction $V$, it may induce nearest-neighbor-p pairing to become the preferred pairing symmetry. Our results provide useful information to identify the dominant superconducting pairing symmetry in the ${A}\mathrm{V}_{3}\mathrm{Sb}_{5}$ family.

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Anomalous Hall effect and electronic correlation in a spin-reoriented kagome antiferromagnet LuFe6Sn6 Meng Lyu(吕孟), Yang Liu(刘洋), Shen Zhang(张伸), Junyan Liu(刘俊艳), Jinying Yang(杨金颖), Yibo Wang(王一博), Yiting Feng(冯乙婷), Xuebin Dong(董学斌), Binbin Wang(王彬彬), Hongxiang Wei(魏红祥), and Enke Liu(刘恩克) Chin. Phys. B, 2024, 33 (10):  107507.  DOI: 10.1088/1674-1056/ad6f93 Abstract ( 73 )   HTML ( 0 )   PDF (1289KB) ( 98 )   The kagome lattice system has been identified as a fertile ground for the emergence of a number of new quantum states, including superconductivity, quantum spin liquids, and topological electronic states. This has attracted significant interest within the field of condensed matter physics. Here, we present the observation of an anomalous Hall effect in an iron-based kagome antiferromagnet LuFe$_{6}$Sn$_{6}$, which implies a non-zero Berry curvature in this compound. By means of extensive magnetic measurements, a high Neel temperature, $T_{\rm N} = 552 $ K, and a spin reorientation behavior were identified and a simple temperature-field phase diagram was constructed. Furthermore, this compound was found to exhibit a large Sommerfeld coefficient of $\gamma = 87 $ mJ$\cdot $mol$^{-1}\cdot$K$^{-2}$, suggesting the presence of a strong electronic correlation effect. Our research indicates that LuFe$_{6}$Sn$_{6}$ is an intriguing compound that may exhibit magnetism, strong correlation, and topological states.

DATA PAPER

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Fully relativistic energies, transition properties, and lifetimes of lithium-like germanium Shuang Li(李双), Jing Zhou(周璟), Liu-Hong Zhu(朱柳红), Xiu-Fei Mei(梅秀菲), and Jun Yan(颜君) Chin. Phys. B, 2024, 33 (10):  103102.  DOI: 10.1088/1674-1056/ad7c30 Abstract ( 75 )   HTML ( 1 )   PDF (628KB) ( 83 )   Employing two fully relativistic methods, the multi-reference configuration Dirac-Hartree-Fock (MCDHF) method and the relativistic many-body perturbation theory (RMBPT) method, we report energies and lifetime values for the lowest 35 energy levels of the (1s$^2)nl$ configurations (where the principal quantum number $n = 2$-6 and the angular quantum number $l = 0$, …, $n-1$) of lithium-like germanium (Ge XXX), as well as complete data on the transition wavelengths, radiative rates, absorption oscillator strengths, and line strengths between the levels. Both the allowed (E1) and forbidden (magnetic dipole M1, magnetic quadrupole M2, and electric quadrupole E2) ones are reported. The results from the two methods are consistent with each other and align well with previous accurate experimental and theoretical findings. We assess the overall accuracies of present RMBPT results to be likely the most precise ones to date. The present fully relativistic results should be helpful for soft x-ray laser research, spectral line identification, plasma modeling and diagnosing. The datasets presented in this paper are openly available at https://doi.org/10.57760/sciencedb.j00113.00135.

COMPUTATIONAL PROGRAMS FOR PHYSICS

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Charge self-consistent dynamical mean field theory calculations in combination with linear combination of numerical atomic orbitals framework based density functional theory Xin Qu(瞿鑫), Peng Xu(许鹏), Zhiyong Liu(刘志勇), Jintao Wang(王金涛), Fei Wang(王飞), Wei Huang(黄威), Zhongxin Li(李忠星), Weichang Xu(徐卫昌), and Xinguo Ren(任新国) Chin. Phys. B, 2024, 33 (10):  107106.  DOI: 10.1088/1674-1056/ad6558 Abstract ( 70 )   HTML ( 3 )   PDF (840KB) ( 95 )   We present a formalism of charge self-consistent dynamical mean field theory (DMFT) in combination with density functional theory (DFT) within the linear combination of numerical atomic orbitals (LCNAO) framework. We implemented the charge self-consistent $\rm DFT+DMFT$ formalism by interfacing a full-potential all-electron DFT code with three hybridization expansion-based continuous-time quantum Monte Carlo impurity solvers. The benchmarks on several 3d, 4f and 5f strongly correlated electron systems validated our formalism and implementation. Furthermore, within the LCANO framework, our formalism is general and the code architecture is extensible, so it can work as a bridge merging different LCNAO DFT packages and impurity solvers to do charge self-consistent $\rm DFT+DMFT$ calculations.

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MicroMagnetic.jl: A Julia package for micromagnetic and atomistic simulations with GPU support Weiwei Wang(王伟伟), Boyao Lyu(吕伯尧), Lingyao Kong(孔令尧), Hans Fangohr, and Haifeng Du(杜海峰) Chin. Phys. B, 2024, 33 (10):  107508.  DOI: 10.1088/1674-1056/ad766f Abstract ( 73 )   HTML ( 2 )   PDF (919KB) ( 45 )   MicroMagnetic.jl is an open-source Julia package for micromagnetic and atomistic simulations. Using the features of the Julia programming language, MicroMagnetic.jl supports CPU and various GPU platforms, including NVIDIA, AMD, Intel, and Apple GPUs. Moreover, MicroMagnetic.jl supports Monte Carlo simulations for atomistic models and implements the nudged-elastic-band method for energy barrier computations. With built-in support for double and single precision modes and a design allowing easy extensibility to add new features, MicroMagnetic.jl provides a versatile toolset for researchers in micromagnetics and atomistic simulations.

RAPID COMMUNICATION

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Impact of asymptomatic infected individuals on epidemic transmission dynamics in multiplex networks with partial coupling Xin Hu(胡鑫), Jiaxing Chen(陈嘉兴), and Chengyi Xia(夏承遗) Chin. Phys. B, 2024, 33 (10):  100202.  DOI: 10.1088/1674-1056/ad757b Abstract ( 80 )   HTML ( 4 )   PDF (996KB) ( 112 )   The theory of network science has attracted great interest of many researchers in the realm of biomathematics and public health, and numerous valuable epidemic models have been developed. In previous studies, it is common to set up a one-to-one correspondence between the nodes of a multi-layer network, ignoring the more complex situations in reality. In the present work, we explore this situation by setting up a partially coupled model of a two-layer network and investigating the impact of asymptomatic infected individuals on epidemics. We propose a self-discovery mechanism for asymptomatic infected individuals, taking into account situations such as nucleic acid testing in the community and individuals performing self-antigen testing during the epidemic. Considering these factors together, through the microscopic Markov chain approach (MMCA) and extensive Monte Carlo (MC) numerical simulations, we find that the greater the coupling between the networks, the more information dissemination is facilitated. In order to control the epidemics, more asymptomatic infected individuals should be made aware of their infection. Massive adoption of nucleic acid testing and individual adoption of antigenic self-testing can help to contain epidemic outbreaks. Meanwhile, the epidemic threshold of the proposed model is derived, and then miscellaneous factors affecting the epidemic threshold are also discussed. Current results are conducive to devising the prevention and control policies of pandemics.

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Pressure-induced structural, electronic, and superconducting phase transitions in TaSe3 Hot! Yuhang Li(李宇航), Pei Zhou(周佩), Chi Ding(丁驰), Qing Lu(鲁清), Xiaomeng Wang(王晓梦), and Jian Sun(孙建) Chin. Phys. B, 2024, 33 (10):  106102.  DOI: 10.1088/1674-1056/ad6f92 Abstract ( 350 )   HTML ( 24 )   PDF (2643KB) ( 313 )   TaSe$_{3}$ has garnered significant research interests due to its unique quasi-one-dimensional crystal structure, which gives rise to distinctive properties. Using crystal structure search and first-principles calculations, we systematically investigated the pressure-induced structural and electronic phase transitions of quasi-one-dimensional TaSe$_{3}$ up to 100 GPa. In addition to the ambient pressure phase ($P2_{1}/m$-I), we identified three high-pressure phases: $P2_{1}/m$-II, Pnma, and Pmma. For the $P2_{1}/m$-I phase, the inclusion of spin-orbit coupling (SOC) results in significant SOC splitting and changes in the band inversion characteristics. Furthermore, band structure calculations for the three high-pressure phases indicate metallic natures, and the electron localization function suggests ionic bonding between Ta and Se atoms. Our electron-phonon coupling calculations reveal a superconducting critical temperature of approximately 6.4 K for the Pmma phase at 100 GPa. This study provides valuable insights into the high-pressure electronic behavior of quasi-one-dimensional TaSe$_{3}$.

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Pit density reduction for AlN epilayers grown by molecular beam epitaxy using Al modulation method Huan Liu(刘欢), Peng-Fei Shao(邵鹏飞), Song-Lin Chen(陈松林), Tao Tao(陶涛), Yu Yan(严羽), Zi-Li Xie(谢自力), Bin Liu(刘斌), Dun-Jun Chen(陈敦军), Hai Lu(陆海), Rong Zhang(张荣), and Ke Wang(王科) Chin. Phys. B, 2024, 33 (10):  106801.  DOI: 10.1088/1674-1056/ad7671 Abstract ( 65 )   HTML ( 1 )   PDF (1758KB) ( 91 )   We have investigated homoepitaxy of AlN films grown by molecular beam epitaxy on AlN/sapphire templates by adopting both the continuous growth method and the Al modulation epitaxy (AME) growth method. The continuous growth method encounters significant challenges in controlling the growth mode. As the precise $\rm Al/N=1.0$ ratio is difficult to achieve, either the excessive Al-rich or N-rich growth mode occurs. In contrast, by adopting the AME growth method, such a difficulty has been effectively overcome. By manipulating the supply time of the Al and nitrogen sources, we were able to produce AlN films with much improved surface morphology. The first step of the AME method, only supplying Al atoms, is important to wet the surface and the Al adatoms can act as a surfactant. Optimization of the initial Al supply time can effectively reduce the pit density on the grown AlN surface. The pits density dropped from 12 pitsμm$^2$ to 1 pitμm$^2$ and the surface roughness reduced from 0.72 nm to 0.3 nm in a $2\times 2 $ μm$^2$ area for the AME AlN film homoepitaxially grown on an AlN template.

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Regulating Anderson localization with structural defect disorder Hot! Mouyang Cheng(程谋阳), Haoxiang Chen(陈浩翔), and Ji Chen(陈基) Chin. Phys. B, 2024, 33 (10):  107201.  DOI: 10.1088/1674-1056/ad711c Abstract ( 183 )   HTML ( 15 )   PDF (1916KB) ( 170 )   Localization due to disorder has been one of the most intriguing theoretical concepts that evolved in condensed matter physics. Here, we expand the theory of localization by considering two types of disorders at the same time, namely, the original Anderson's disorder and the structural defect disorder, which has been suggested to be a key component in recently discovered two-dimensional amorphous materials. While increasing the degree of both disorders could induce localization of wavefunction in real space, we find that a small degree of structural defect disorder can significantly enhance the localization. As the degree of structural defect disorder increases, localized states quickly appear within the extended phase to enter a broad crossover region with mixed phases. We establish two-dimensional diagrams for the wavefunction localization and conductivity to highlight the interplay between the two types of disorders. Our theoretical model provides a comprehensive understanding of localization in two-dimensional amorphous materials and highlights the promising tunability of their transport properties.

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Role of self-assembled molecules' anchoring groups for surface defect passivation and dipole modulation in inverted perovskite solar cells Hot! Xiaoyu Wang(王啸宇), Muhammad Faizan, Kun Zhou(周琨), Xinjiang Wang(王新江), Yuhao Fu(付钰豪), and Lijun Zhang(张立军) Chin. Phys. B, 2024, 33 (10):  107303.  DOI: 10.1088/1674-1056/ad711f Abstract ( 174 )   HTML ( 11 )   PDF (1547KB) ( 150 )   Inverted perovskite solar cells have gained prominence in industrial advancement due to their easy fabrication, low hysteresis effects, and high stability. Despite these advantages, their efficiency is currently limited by excessive defects and poor carrier transport at the perovskite-electrode interface, particularly at the buried interface between the perovskite and transparent conductive oxide (TCO). Recent efforts in the perovskite community have focused on designing novel self-assembled molecules (SAMs) to improve the quality of the buried interface. However, a notable gap remains in understanding the regulation of atomic-scale interfacial properties of SAMs between the perovskite and TCO interfaces. This understanding is crucial, particularly in terms of identifying chemically active anchoring groups. In this study, we used the star SAM ([2-(9H-carbazol-9-yl)ethyl] phosphonic acid) as the base structure to investigate the defect passivation effects of eight common anchoring groups at the perovskite-TCO interface. Our findings indicate that the phosphonic and boric acid groups exhibit notable advantages. These groups fulfill three key criteria: they provide the greatest potential for defect passivation, exhibit stable adsorption with defects, and exert significant regulatory effects on interface dipoles. Ionized anchoring groups exhibit enhanced passivation capabilities for defect energy levels due to their superior Lewis base properties, which effectively neutralize local charges near defects. Among various defect types, iodine vacancies are the easiest to passivate, whereas iodine-substituted lead defects are the most challenging to passivate. Our study provides comprehensive theoretical insights and inspiration for the design of anchoring groups in SAMs, contributing to the ongoing development of more efficient inverted perovskite solar cells.

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Hot carrier cooling in lead halide perovskites probed by two-pulse photovoltage correlation spectroscopy Hot! Yuqing Huang(黄玉清), Chaoyu Guo(郭钞宇), Lei Gao(高蕾), Wenna Du(杜文娜), Haotian Zheng(郑浩天), Da Wu(吴达), Zhengpu Zhao(赵正朴), Chu-Wei Zhang(张楚惟), Qin Wang(王钦), Xin-Feng Liu(刘新风), Qingfeng Yan(严清峰), and Ying Jiang(江颖) Chin. Phys. B, 2024, 33 (10):  107304.  DOI: 10.1088/1674-1056/ad7728 Abstract ( 113 )   HTML ( 11 )   PDF (1507KB) ( 147 )   The next-generation hot-carrier solar cells, which can overcome the Shockley-Queisser limit by harvesting excess energy from hot carriers, are receiving increasing attention. Lead halide perovskite (LHP) materials are considered as promising candidates due to their exceptional photovoltaic properties, good stability and low cost. The cooling rate of hot carriers is a key parameter influencing the performance of hot-carrier solar cells. In this work, we successfully detected hot carrier dynamics in operando LHP devices using the two-pulse photovoltage correlation technique. To enhance the signal-to-noise ratio, we applied the delay-time modulation method instead of the traditional power modulation. This advancement allowed us to detect the intraband hot carrier cooling time for the organic LHP CH$_{3}$NH$_{3}$PbBr$_{3}$, which is as short as 0.21 ps. In comparison, the inorganic Cs-based LHP CsPbBr$_{3}$ exhibited a longer cooling time of around 0.59 ps due to different phonon contributions. These results provide us new insights into the optimal design of hot-carrier solar cells and highlight the potential of LHP materials in advancing solar cell technology.

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Structural color of metallic glass through picosecond laser Hot! Yue'e Zhang(张月娥), Xing Tong(童星), Yuqiang Yan(闫玉强), Shuo Cao(曹硕), Hai-Bo Ke(柯海波), and Wei-Hua Wang(汪卫华) Chin. Phys. B, 2024, 33 (10):  108104.  DOI: 10.1088/1674-1056/ad7672 Abstract ( 131 )   HTML ( 3 )   PDF (4179KB) ( 126 )   The alteration in surface color of metallic glasses (MGs) holds great significance in the context of microstructure design and commercial utility. It is essential to accurately describe the structures that are formed during the laser and color separation processes in order to develop practical laser coloring applications. Due to the high oxidation sensitivity of La-based metallic glass, it can broaden the color range but make it more complex. Structure coloring by laser processing on the surface of La-based metallic glass can be conducted after thermoplastic forming. It is particularly important to clarify the role of structure and composition in the surface coloring process. The aim is to study the relationship between amorphous surface structural color, surface geometry, and oxide formation by laser processing in metallic glasses. The findings revealed that the periodic structure primarily determines the surface color at laser energy densities below 1.0 J/mm$^{2}$. In contrast, the surface color predominantly depends on the proportion of oxides that are formed when energy densities exceed 1.0 J/mm$^{2}$. Consequently, this study provides a novel concept for the fundamental investigation of laser coloring and establishes a new avenue for practical application.

GENERAL

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On fractional discrete financial system: Bifurcation, chaos, and control Louiza Diabi, Adel Ouannas, Amel Hioual, Shaher Momani, and Abderrahmane Abbes Chin. Phys. B, 2024, 33 (10):  100201.  DOI: 10.1088/1674-1056/ad5d96 Abstract ( 64 )   HTML ( 0 )   PDF (4344KB) ( 44 )   The dynamic analysis of financial systems is a developing field that combines mathematics and economics to understand and explain fluctuations in financial markets. This paper introduces a new three-dimensional (3D) fractional financial map and we dissect its nonlinear dynamics system under commensurate and incommensurate orders. As such, we evaluate when the equilibrium points are stable or unstable at various fractional orders. We use many numerical methods, phase plots in 2D and 3D projections, bifurcation diagrams and the maximum Lyapunov exponent. These techniques reveal that financial maps exhibit chaotic attractor behavior. This study is grounded on the Caputo-like discrete operator, which is specifically influenced by the variance of the commensurate and incommensurate orders. Furthermore, we confirm the presence and measure the complexity of chaos in financial maps by the 0-1 test and the approximate entropy algorithm. Additionally, we offer nonlinear-type controllers to stabilize the fractional financial map. The numerical results of this study are obtained using MATLAB.

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Single pair of charge-2 Dirac and charge-2 Weyl phonons in GeO2 Dong-Chang He(何东昌), Jia-Xi Liu(刘嘉希), Pei-Tao Liu(刘培涛), Jiang-Xu Li(李江旭), and Xing-Qiu Chen(陈星秋) Chin. Phys. B, 2024, 33 (10):  100301.  DOI: 10.1088/1674-1056/ad6a08 Abstract ( 85 )   HTML ( 0 )   PDF (3575KB) ( 16 )   The presence of a pair of Weyl and Dirac points (WP-DP) in topological semimetal states is intriguing and sought after due to the effects associated with chiral topological charges. However, identifying these states in real materials poses a significant challenge. In this study, by means of first-principles calculations we predict the coexistence of charge-2 Dirac and charge-2 Weyl phonons at high-symmetry points within a noncentrosymmetric $P4_12_12$ space group. Furthermore, we propose GeO$_2$ as an ideal candidate for realizing these states. Notably, we observe two distinct surface arcs that connect the Dirac and Weyl points across the entire Brillouin zone, which could facilitate their detection in future experimental investigations. This study not only presents a tangible material for experimentalists to explore the topological properties of WP-DP states but also opens up new avenues in the quest for ideal platforms to study chiral particles.

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Reference-frame-independent quantum key distribution with two-way classical communication Chun Zhou(周淳), Hai-Tao Wang(汪海涛), Yi-Fei Lu(陆宜飞), Xiao-Lei Jiang(姜晓磊), Yan-Mei Zhao(赵燕美), Yu Zhou(周雨), Yang Wang(汪洋), Jia-Ji Li(李家骥), Yan-Yang Zhou(周砚扬), Xiang Wang(汪翔), Hong-Wei Li(李宏伟), and Wan-Su Bao(鲍皖苏) Chin. Phys. B, 2024, 33 (10):  100302.  DOI: 10.1088/1674-1056/ad6a3d Abstract ( 68 )   HTML ( 0 )   PDF (568KB) ( 44 )   The data post-processing scheme based on two-way classical communication (TWCC) can improve the tolerable bit error rate and extend the maximal transmission distance when used in a quantum key distribution (QKD) system. In this study, we apply the TWCC method to improve the performance of reference-frame-independent quantum key distribution (RFI-QKD), and analyze the influence of the TWCC method on the performance of decoy-state RFI-QKD in both asymptotic and non-asymptotic cases. Our numerical simulation results show that the TWCC method is able to extend the maximal transmission distance from 175 km to 198 km and improve the tolerable bit error rate from 10.48% to 16.75%. At the same time, the performance of RFI-QKD in terms of the secret key rate and maximum transmission distance are still greatly improved when statistical fluctuations are considered. We conclude that RFI-QKD with the TWCC method is of practical interest.

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Interference-induced suppression of particle emission from a Bose-Einstein condensate in lattice with time-periodic modulations Long-Quan Lai(赖龙泉) and Zhao Li(李照) Chin. Phys. B, 2024, 33 (10):  100303.  DOI: 10.1088/1674-1056/ad607b Abstract ( 66 )   HTML ( 1 )   PDF (1508KB) ( 61 )   Emission of matter-wave jets from a parametrically driven condensate has attracted significant experimental and theoretical attention due to the appealing visual effects and potential metrological applications. In this work, we investigate the collective particle emission from a Bose-Einstein condensate confined in a one-dimensional lattice with periodically modulated interparticle interactions. We give the regimes for discrete modes, and find that the emission can be distinctly suppressed. The configuration induces a broad band, but few particles are ejected due to the interference of the matter waves. We further qualitatively model the emission process and demonstrate the short-time behaviors. This engineering provides a way to manipulate the propagation of particles and the corresponding dynamics of condensates in lattices, and may find application in the dynamical excitation control of other nonequilibrium problems with time-periodic driving.

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Bessel vortices in spin-1 Bose-Einstein condensates with Zeeman splitting and spin-orbit coupling Huan-Bo Luo(罗焕波), Xin-Feng Zhang(张鑫锋), Runhua Li(李润华), Yongyao Li(黎永耀), and Bin Liu(刘彬) Chin. Phys. B, 2024, 33 (10):  100304.  DOI: 10.1088/1674-1056/ad6424 Abstract ( 73 )   HTML ( 0 )   PDF (2456KB) ( 91 )   We investigate the ground states of spin-orbit coupled spin-1 Bose-Einstein condensates in the presence of Zeeman splitting. By introducing the generalized momentum operator, the linear version of the system is solved exactly, yielding a set of Bessel vortices. Additionally, based on linear solution and using variational approximation, the solutions for the full nonlinear system and their ground state phase diagrams are derived, including the vortex states with quantum numbers $m=0$, 1, as well as mixed states. In this work, mixed states in spin-1 spin-orbit coupling (SOC) BEC are interpreted for the first time as weighted superpositions of three vortex states. Furthermore, the results also indicate that under strong Zeeman splitting, the system cannot form localized states. The variational solutions align well with numerical simulations, showing stable evolution and meeting the criteria for long-term observation in experiments.

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Freezing imaginarity of quantum states based on ℓ1-norm Shuo Han(韩烁), Bingke Zheng(郑冰轲), and Zhihua Guo(郭志华) Chin. Phys. B, 2024, 33 (10):  100306.  DOI: 10.1088/1674-1056/ad7c2f Abstract ( 46 )   HTML ( 1 )   PDF (570KB) ( 76 )   We discuss freezing of quantum imaginarity based on $\ell_1$-norm. Several properties about a quantity of imaginarity based on $\ell_1$-norm are revealed. For a qubit (2-dimensional) system, we characterize the structure of real quantum operations that allow for freezing the quantity of imaginarity of any state. Furthermore, we characterize the structure of local real operations which can freeze the quantity of imaginarity of a class of $N$-qubit quantum states.

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Memristors-coupled neuron models with multiple firing patterns and homogeneous and heterogeneous multistability Xuan Wang(王暄), Santo Banerjee, Yinghong Cao(曹颖鸿), and Jun Mou(牟俊) Chin. Phys. B, 2024, 33 (10):  100501.  DOI: 10.1088/1674-1056/ad6256 Abstract ( 61 )   HTML ( 0 )   PDF (12089KB) ( 75 )   Memristors are extensively used to estimate the external electromagnetic stimulation and synapses for neurons. In this paper, two distinct scenarios, i.e., an ideal memristor serves as external electromagnetic stimulation and a locally active memristor serves as a synapse, are formulated to investigate the impact of a memristor on a two-dimensional Hindmarsh-Rose neuron model. Numerical simulations show that the neuronal models in different scenarios have multiple burst firing patterns. The introduction of the memristor makes the neuronal model exhibit complex dynamical behaviors. Finally, the simulation circuit and DSP hardware implementation results validate the physical mechanism, as well as the reliability of the biological neuron model.

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Effective regulation of the interaction process among three optical solitons Houhui Yi(伊厚会), Xiaofeng Li(李晓凤), Junling Zhang(张俊玲), Xin Zhang(张鑫), and Guoli Ma(马国利) Chin. Phys. B, 2024, 33 (10):  100502.  DOI: 10.1088/1674-1056/ad6b87 Abstract ( 68 )   HTML ( 0 )   PDF (1820KB) ( 78 )   The interaction between three optical solitons is a complex and valuable research direction, which is of practical application for promoting the development of optical communication and all-optical information processing technology. In this paper, we start from the study of the variable-coefficient coupled higher-order nonlinear Schrödinger equation (VCHNLSE), and obtain an analytical three-soliton solution of this equation. Based on the obtained solution, the interaction of the three optical solitons is explored when they are incident from different initial velocities and phases. When the higher-order dispersion and nonlinear functions are sinusoidal, hyperbolic secant, and hyperbolic tangent functions, the transmission properties of three optical solitons before and after interactions are discussed. Besides, this paper achieves effective regulation of amplitude and velocity of optical solitons as well as of the local state of interaction process, and interaction-free transmission of the three optical solitons is obtained with a small spacing. The relevant conclusions of the paper are of great significance in promoting the development of high-speed and large-capacity optical communication, optical signal processing, and optical computing.

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Optimization performance of quantum endoreversible Otto machines with dual-squeezed reservoirs Haoguang Liu(刘浩广) Chin. Phys. B, 2024, 33 (10):  100503.  DOI: 10.1088/1674-1056/ad6252 Abstract ( 68 )   HTML ( 0 )   PDF (662KB) ( 26 )   We consider a quantum endoreversible Otto engine cycle and its inverse operation-Otto refrigeration cycle, employing two-level systems as the working substance and operating in dual-squeezed reservoirs. We demonstrate that the efficiency of heat engines at maximum work output and the coefficient of performance for refrigerators at the maximum $\chi$ criterion will degenerate to $ \eta_-=\eta_{\rm C}/(2-\eta_{\rm C})$ and $ \varepsilon_-=(\sqrt{9+8\varepsilon_{\rm C}}-3)/2$ when symmetric squeezing is satisfied, respectively. We also investigated the influences of squeezing degree on the performance optimization of quantum Otto heat engines at the maximum work output and refrigerators at the maximum $\chi$ criterion. These analytical results show that the efficiency of heat engines at maximum work output and the coefficient of performance for refrigerators at the maximum $\chi$ criterion can be improved, reduced or even inhibited in asymmetric squeezing. Furthermore, we also find that the efficiency of quantum Otto heat engines at maximum work output is lower than that obtained from the Otto heat engines based on a single harmonic oscillator system. However, the coefficient of performance of the corresponding refrigerator is higher.

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Thermodynamics of charged AdS black hole surrounded by quintessence in restricted phase space Siyu Jian(简思雨), Siying Long(龙思颖), Juhua Chen(陈菊华), and Yongjiu Wang(王永久) Chin. Phys. B, 2024, 33 (10):  100504.  DOI: 10.1088/1674-1056/ad624f Abstract ( 56 )   HTML ( 0 )   PDF (667KB) ( 85 )   We study thermodynamics of charged AdS black hole surrounded by quintessence in a new formalism which is called the restricted phase space thermodynamics. This context is based on Visser's holographic thermodynamics with a fixed anti-de Sitter radius and a variable Newton constant. The conjugate variables, central charge $C$ and the chemical potential $\mu$, are introduced as a new pair of thermodynamic variables. We find that the iso-e-charge $T$-$S$ curve becomes non-monotonic when $\hat{Q}<\hat{Q}_{\rm c}$. Correspondingly, the $F$-$T$ curve exhibits a swallow tail structure. This behavior is considered as a van der Waals-like phase transition. As the value of $\hat{b}$ related to the energy density of Kiselev's fluid becomes larger, the critical temperature $T_{\rm c}$ will decrease. Thus, the van der Waals-like phase transition will occur at lower temperature. There is always a non-quilibrium transition from a small unstable black hole to a large stable black hole state in the isocoltage $T$-$S$ process. There exist a maximum and a Hawking-Page phase transition points in the $\mu$-$C$ plane. As the value of $\hat{b}$ related to Kiselev's fluid becomes larger, the Hawking-Page phase transition will occur at lower temperature in the isovoltage $\mu$-$T$ process. For other values of the state parameter $\omega$, there also exists van der Waals-like phase transition.

ATOMIC AND MOLECULAR PHYSICS

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Geometric properties of the first singlet S-wave excited state of two-electron atoms near the critical nuclear charge Tong Chen(陈彤), Sanjiang Yang(杨三江), Wanping Zhou(周挽平), Xuesong Mei(梅雪松), and Haoxue Qiao(乔豪学) Chin. Phys. B, 2024, 33 (10):  103101.  DOI: 10.1088/1674-1056/ad6422 Abstract ( 71 )   HTML ( 0 )   PDF (803KB) ( 13 )   The geometric structure parameters and radial density distribution of 1s2s$\,^1$S excited state of the two-electron atomic system near the critical nuclear charge $Z_{\rm c}$ were calculated in detail under tripled Hylleraas basis set. Contrary to the localized behavior observed in the ground and the doubly excited 2p$^2\,^3{\rm P}^{\rm e}$ states, for this state our results identify that while the behavior of the inner electron increasingly resembles that of a hydrogen-like atomic system, the outer electron in the excited state exhibits diffused hydrogen-like character and becomes perpendicular to the inner electron as nuclear charge $Z$ approaches $Z_{\rm c}$. This study provides insights into the electronic structure and stability of the two-electron system in the vicinity of the critical nuclear charge.

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Photoelectron momentum distributions of triatomic CO2 molecules by circularly polarized attosecond pulses Si-Qi Zhang(张思琪), Jun Zhang(张军), Xin-Yu Hao(郝欣宇), Jing Guo(郭静), Aihua Liu(刘爱华), and Xue-Shen Liu(刘学深) Chin. Phys. B, 2024, 33 (10):  103301.  DOI: 10.1088/1674-1056/ad6b81 Abstract ( 98 )   HTML ( 0 )   PDF (2477KB) ( 105 )   Molecular-frame photoelectron momentum distributions (MF-PMDs) have been studied for imaging molecular structures. We investigate the MF-PMDs of CO$_{2}$ molecules exposed to circularly polarized (CP) attosecond laser pulses by solving the time-dependent Schrödinger equations based on the single-active-electron approximation frames. Results show that high-frequency photons lead to photoelectron diffraction patterns, indicating molecular orbitals. These diffraction patterns can be illustrated by the ultrafast photoionization models. However, for the driving pulses with 30 nm, a deviation between MF-PMDs and theoretically predicted results of the ultrafast photoionization models is produced because the Coulomb effect strongly influences the molecular photoionization. Meanwhile, the MF-PMDs rotate in the same direction as the helicity of driving laser pulses. Our results also demonstrate that the MF-PMDs in a CP laser pulse are the superposition of those in the parallel and perpendicular linearly polarized cases. The simulations efficiently visualize molecular orbital geometries and structures by ultrafast photoelectron imaging. Furthermore, we determine the contribution of HOMO and HOMO-1 orbitals to ionization by varying the relative phase and the ratio of these two orbitals.

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

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Imaging through scattering layers using a near-infrared low-spatial-coherence fiber random laser Anda Shi(史安达), Zeyu Wang(王泽宇), Chenxi Duan(段辰锡), Zhao Wang(王昭), and Weili Zhang(张伟利) Chin. Phys. B, 2024, 33 (10):  104202.  DOI: 10.1088/1674-1056/ad6420 Abstract ( 87 )   HTML ( 0 )   PDF (1593KB) ( 97 )   Optical memory effect-based speckle-correlated technology has been developed for reconstructing hidden objects from disordered speckle patterns, achieving imaging through scattering layers. However, the lighting efficiency and field of view of existing speckle-correlated imaging systems are limited. Here, a near-infrared low spatial coherence fiber random laser illumination method is proposed to address the above limitations. Through the utilization of random Rayleigh scattering within dispersion-shifted fibers to provide feedback, coupled with stimulated Raman scattering for amplification, a near-infrared fiber random laser exhibiting a high spectral density and extremely low spatial coherence is generated. Based on the designed fiber random laser, speckle-correlated imaging through scattering layers is achieved, with high lighting efficiency and a large imaging field of view. This work improves the performance of speckle-correlated imaging and enriches the research on imaging through scattering medium.

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Reconstruction algorithm for cross-waveband optical computing imaging Jin-Tao Xie(谢锦涛), Shu-Hang Bie(别书航), Ming-Fei Li(李明飞), Yuan-Jin Yu(余远金), Yi-Fei Li(李毅飞), Jin-Guang Wang(王进光), Bao-Gang Quan(全保刚), and Ling-An Wu(吴令安) Chin. Phys. B, 2024, 33 (10):  104203.  DOI: 10.1088/1674-1056/ad6ccc Abstract ( 60 )   HTML ( 0 )   PDF (1918KB) ( 90 )   In a single-pixel fast imaging setup, the data collected by the single-pixel detector needs to be processed by a computer, but the speed of the latter will affect the image reconstruction time. Here we propose two kinds of setups which are able to transform non-visible into visible light imaging, wherein their computing process is replaced by a camera integration mode. The image captured by the camera has a low contrast, so here we present an algorithm that can realize a high quality image in near-infrared to visible cross-waveband imaging. The scheme is verified both by simulation and in actual experiments. The setups demonstrate the great potential for single-pixel imaging and high-speed cross-waveband imaging for future practical applications.

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Presentation of the Berry-Tabor conjecture in Lévy plates Chao Li(李超) and Guo-Lin Hou(侯国林) Chin. Phys. B, 2024, 33 (10):  104204.  DOI: 10.1088/1674-1056/ad21f2 Abstract ( 62 )   HTML ( 0 )   PDF (875KB) ( 15 )   The Berry-Tabor (BT) conjecture is a famous statistical inference in quantum chaos, which not only establishes the spectral fluctuations of quantum systems whose classical counterparts are integrable but can also be used to describe other wave phenomena. In this paper, the BT conjecture has been extended to Lévy plates. As predicted by the BT conjecture, level clustering is present in the spectra of Lévy plates. The consequence of level clustering is studied by introducing the distribution of nearest neighbor frequency level spacing ratios $P\left({\widetilde r} \right)$, which is calculated through the analytical solution obtained by the Hamiltonian approach. Our work investigates the impact of varying foundation parameters, rotary inertia, and boundary conditions on the frequency spectra, and we find that $P\left({\widetilde r} \right)$ conforms to a Poisson distribution in all cases. The reason for the occurrence of the Poisson distribution in the Lévy plates is the independence between modal frequencies, which can be understood through mode functions.

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Image encryption algorithm based on multiple chaotic systems and improved Joseph block scrambling Dingkang Mou(牟定康) and Yumin Dong(董玉民) Chin. Phys. B, 2024, 33 (10):  104205.  DOI: 10.1088/1674-1056/ad6257 Abstract ( 68 )   HTML ( 1 )   PDF (16192KB) ( 59 )   With the rapid development of digital information technology, images are increasingly used in various fields. To ensure the security of image data, prevent unauthorized tampering and leakage, maintain personal privacy, and protect intellectual property rights, this study proposes an innovative color image encryption algorithm. Initially, the Mersenne Twister algorithm is utilized to generate high-quality pseudo-random numbers, establishing a robust basis for subsequent operations. Subsequently, two distinct chaotic systems, the autonomous non-Hamiltonian chaotic system and the tent-logistic-cosine chaotic mapping, are employed to produce chaotic random sequences. These chaotic sequences are used to control the encoding and decoding process of the DNA, effectively scrambling the image pixels. Furthermore, the complexity of the encryption process is enhanced through improved Joseph block scrambling. Thorough experimental verification, research, and analysis, the average value of the information entropy test data reaches as high as 7.999. Additionally, the average value of the number of pixels change rate (NPCR) test data is 99.6101%, which closely approaches the ideal value of 99.6094%. This algorithm not only guarantees image quality but also substantially raises the difficulty of decryption.

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Statistical properties of ideal photons in a two-dimensional dye-filled spherical cap cavity Ze Cheng(成泽) Chin. Phys. B, 2024, 33 (10):  104206.  DOI: 10.1088/1674-1056/ad6cc9 Abstract ( 86 )   HTML ( 2 )   PDF (660KB) ( 91 )   Within the framework of quantum statistical mechanics, we have proposed an exact analytical solution to the problem of Bose-Einstein condensation (BEC) of harmonically trapped two-dimensional (2D) ideal photons. We utilize this analytical solution to investigate the statistical properties of ideal photons in a 2D dye-filled spherical cap cavity. The results of numerical calculation of the analytical solution agree completely with the foregoing experimental results in the BEC of harmonically trapped 2D ideal photons. The analytical expressions of the critical temperature and the condensate fraction are derived in the thermodynamic limit. It is found that the 2D critical photon number is larger than the one-dimensional (1D) critical photon number by two orders of magnitude. The spectral radiance of a 2D spherical cap cavity has a sharp peak at the frequency of the cavity cutoff when the photon number exceeds the critical value determined by a temperature.

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Third-order nonlinear wavelength conversion in chalcogenide glass waveguides towards mid-infrared photonics Fengbo Han(韩锋博), Jiaxin Gu(顾佳新), Lu Huang(黄璐), Hang Wang(王航), Yali Huang(黄雅莉), Xuecheng Zhou(周学成), Shaoliang Yu(虞绍良), Zhengqian Luo(罗正钱), Zhipeng Dong(董志鹏), and Qingyang Du(杜清扬) Chin. Phys. B, 2024, 33 (10):  104207.  DOI: 10.1088/1674-1056/ad6557 Abstract ( 62 )   HTML ( 0 )   PDF (1941KB) ( 93 )   The increasing demand in spectroscopy and sensing calls for infrared (mid-IR) light sources. Here, we theoretically investigate nonlinear wavelength conversion of Ge$_{28}$Sb$_{12}$Se$_{60}$ chalcogenide glass waveguide in the mid-IR spectral regime. With waveguide dispersion engineering, we predict generation of over an octave wavelength (2.8 μm-5.9 μm) tuning range Raman soliton self-frequency shift, over 2.5 octaves wavelength cover range supercontinuum (1.2 μm-8.0 μm), as well as single soliton Kerr comb generated in suspended Ge$_{28}$Sb$_{12}$Se$_{60}$ waveguide. Our findings evidenced that Ge$_{28}$Sb$_{12}$Se$_{60}$ chalcogenide glass waveguides can simultaneously satisfy the generation of Raman soliton self-frequency shift, supercontinuum spectrum, and Kerr frequency comb generation through dispersion engineering towards mid-IR on chip.

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Broadband third-order optical nonlinearities of layered franckeite towards mid-infrared regime Zhi-Qiang Xu(徐志强), Tian-Tian Zhou(周甜甜), Jie Li(李洁), Dong-Yang Liu(刘东阳), Yuan He(何源), Ning Li(李宁), Xiao Liu(刘潇), Li-Li Miao(缪丽丽), Chu-Jun Zhao(赵楚军), and Shuang-Chun Wen(文双春) Chin. Phys. B, 2024, 33 (10):  104208.  DOI: 10.1088/1674-1056/ad6ccb Abstract ( 57 )   HTML ( 0 )   PDF (931KB) ( 63 )   The study of nonlinear optical responses in the mid-infrared (mid-IR) regime is essential for advancing ultrafast mid-IR laser applications. However, nonlinear optical effects under mid-IR excitation are rarely reported due to the lack of suitable nonlinear optical materials. The natural van der Waals heterostructure franckeite, known for its narrow bandgap and stability in air, shows great potential for developing mid-IR nonlinear optical devices. We have experimentally demonstrated that layered franckeite exhibits a broadband wavelength-dependent nonlinear optical response in the mid-IR spectral region. Franckeite nanosheets were prepared using a liquid-phase exfoliation method, and their nonlinear optical response was characterized in the spectral range of 3000 nm to 5000 nm. The franckeite nanosheets exhibit broadband wavelength-dependent third-order nonlinearities, with nonlinear absorption and refraction coefficients estimated to be about 10$^{-7}$ cm/W and 10$^{-11}$ cm$^{2}$/W, respectively. Additionally, a passively $Q$-switched fluoride fiber laser operating around a wavelength of 2800 nm was achieved, delivering nanosecond pulses with a signal-to-noise ratio of 43.6 dB, based on the nonlinear response of franckeite. These findings indicate that layered franckeite possesses broadband nonlinear optical characteristics in the mid-IR region, potentially enabling new possibilities for mid-IR photonic devices.

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Three-dimensional topological crystalline insulator without spin-orbit coupling in nonsymmorphic photonic metacrystal Zhide Yu(余智德) and Lingbo Xia(夏凌波) Chin. Phys. B, 2024, 33 (10):  104209.  DOI: 10.1088/1674-1056/ad6a3e Abstract ( 59 )   HTML ( 0 )   PDF (1137KB) ( 55 )   By including certain point group symmetry in the classification of band topology, Fu proposed a class of three-dimensional topological crystalline insulators (TCIs) without spin-orbit coupling in 2011. In Fu's model, surface states (if present) doubly degenerate at $\bar{\varGamma }$ and $\bar{M}$ when time-reversal and $C_{4}$ symmetries are preserved. The analogs of Fu's model with surface states quadratically degenerate at $\bar{M}$ are widely studied, while surface states with quadratic degeneracy at $\bar{\varGamma }$ are rarely reported. In this study, we propose a three-dimensional TCI without spin-orbit coupling in a judiciously designed nonsymmorphic photonic metacrystal. The surface states of photonic TCIs exhibit quadratic band degeneracy in the (001) surface Brillouin zone (BZ) center ($\bar{\varGamma }$ point). The gapless surface states and their quadratic dispersion are protected by $C_{4}$ and time-reversal symmetries, which correspond to the nontrivial band topology characterized by ${Z}_{{2}}$ topological invariant. Moreover, the surface states along lines from $\bar{\varGamma }$ to the (001) surface BZ boundary exhibit zigzag feature, which is interpreted from symmetry perspective by building composite operators constructed by the product of glide symmetries with time-reversal symmetry. The metacrystal array surrounded with air possesses high order hinge states with electric fields highly localized at the hinge that may apply to optical sensors. The gapless surface states and hinge states reside in a clean frequency bandgap. The topological surface states emerge at the boundary of the metacrystal and perfect electric conductor (PEC), which provide a pathway for topologically manipulating light propagation in photonic devices.

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Ultra-broadband and wide-angle reflective terahertz polarization conversion metasurface based on topological optimization Ya-Jie Zhang(张亚杰), Chao-Long Li(李潮龙), Jia-Qi Luan(栾迦淇), Ming Zhao(赵茗), Ding-Shan Gao(郜定山), and Pei-Li Li(李培丽) Chin. Phys. B, 2024, 33 (10):  104210.  DOI: 10.1088/1674-1056/ad5d91 Abstract ( 67 )   HTML ( 0 )   PDF (986KB) ( 63 )   Terahertz polarization conversion devices have significant potential applications in various fields such as terahertz imaging and spectroscopy. In this paper, we utilize genetic algorithms to topologically optimize the metasurface unit cells and design a reflective linear polarization conversion metasurface with ultra-broadband and wide-angle characteristics. By partitioning the metallic pattern layer into quadrants, the encoding length is effectively reduced, resulting in a shorter optimization time. The research results indicate that the converter possesses a polarization conversion efficiency ratio higher than 90% and a relative bandwidth ratio of 125% in a range of 0.231-0.995 THz. Meanwhile, it can maintain excellent polarization conversion properties when the incident angle of terahertz waves is less than 45$^\circ$ and the polarization angle is less than 15$^\circ$, demonstrating excellent practicality. New insights are provided for the design of terahertz wide-angle ultra-wideband polarization conversion devices, and the proposed metasurfce has potential applications in terahertz polarization imaging, spectroscopy and communication fields.

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Inverse design of nonlinear phononic crystal configurations based on multi-label classification learning neural networks Kunqi Huang(黄坤琦), Yiran Lin(林懿然), Yun Lai(赖耘), and Xiaozhou Liu(刘晓宙) Chin. Phys. B, 2024, 33 (10):  104301.  DOI: 10.1088/1674-1056/ad6b85 Abstract ( 77 )   HTML ( 0 )   PDF (972KB) ( 85 )   Phononic crystals, as artificial composite materials, have sparked significant interest due to their novel characteristics that emerge upon the introduction of nonlinearity. Among these properties, second-harmonic features exhibit potential applications in acoustic frequency conversion, non-reciprocal wave propagation, and non-destructive testing. Precisely manipulating the harmonic band structure presents a major challenge in the design of nonlinear phononic crystals. Traditional design approaches based on parameter adjustments to meet specific application requirements are inefficient and often yield suboptimal performance. Therefore, this paper develops a design methodology using Softmax logistic regression and multi-label classification learning to inversely design the material distribution of nonlinear phononic crystals by exploiting information from harmonic transmission spectra. The results demonstrate that the neural network-based inverse design method can effectively tailor nonlinear phononic crystals with desired functionalities. This work establishes a mapping relationship between the band structure and the material distribution within phononic crystals, providing valuable insights into the inverse design of metamaterials.

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Ultrasonic scalpel based on fusiform phononic crystal structure Sha Wang(王莎), Junjie Shan(单俊杰), and Shuyu Lin(林书玉) Chin. Phys. B, 2024, 33 (10):  104302.  DOI: 10.1088/1674-1056/ad6a0c Abstract ( 49 )   HTML ( 0 )   PDF (1662KB) ( 9 )   In response to the ultrasonic scalpels with the vibrational modal coupling which leads to a decrease in efficiency, an ultrasonic scalpel based on fusiform phononic crystals (PnCs) is proposed. An accurate theoretical model is constructed, which is mainly composed of electromechanical equivalent circuit models to analyze the frequency response function and the frequency response curves of the admittance. Bragg band gaps exist in the fusiform PnCs owing to the periodic constraint, which can suppress the corresponding vibrational modes. The vibration characteristics (vibration mode, frequency, and displacement distribution) of the ultrasonic scalpel are analyzed, and the validity of the electromechanical equivalent circuit method is verified. The results indicate that other vibration modes near the working frequency can be isolated. In addition, blades based on fusiform PnCs have a function akin to that of the horn, which enables displacement amplification.

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Casson hybrid nanofluid flow over a Riga plate for drug delivery applications with double diffusion Abeer S. Alnahdi and Taza Gul Chin. Phys. B, 2024, 33 (10):  104701.  DOI: 10.1088/1674-1056/ad624e Abstract ( 64 )   HTML ( 1 )   PDF (2095KB) ( 12 )   Casson fluid-mediated hybrid nanofluids are more effective at transferring heat than traditional heat transfer fluids in terms of thermal conductivity. Heat exchangers, cooling systems and other thermal management systems are ideal for use with Casson fluids. Precise control of the flow and release of medication is necessary when using Casson fluids in drug delivery systems because of their unique rheological properties. Nanotechnology involves the creation of nanoparticles that are loaded with drugs and distributed in Casson fluid-based carriers for targeted delivery. In this study, to create a hybrid nanofluid, both single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) are dispersed in a Casson fluid with Fourier's and Fick's laws assumptions. The Casson fluid is suitable for various engineering and medical applications due to the enhancement of heat transfer and thermal conductivity by the carbon nanotubes. Our objective is to understand how SWCNTs and MWCNTs impact the flow field by studying the flow behavior of the Casson hybrid nanofluid when it is stretched against a Riga plate. The Darcy-Forchheimer model is also used to account for the impact of the porous medium near the stretching plate. Both linear and quadratic drag terms are taken into account in this model to accurately predict the flow behavior of the nanofluid. In addition, the homotopy analysis method is utilized to address the model problem. The outcomes are discussed and deliberated based on drug delivery applications. These findings shed valuable light on the flow characteristics of a Casson hybrid nanofluid comprising SWCNTs and MWCNTs. It is observed that the incorporation of carbon nanotubes makes the nanofluid a promising candidate for medical applications due to its improved heat transfer properties.

PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

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Experimental studies of H2/Ar plasma in a cylindrical inductive discharge with an expansion region Shi-Bo Li(李世博), Si-Yu Xing(邢思雨), Fei Gao(高飞), and You-Nian Wang(王友年) Chin. Phys. B, 2024, 33 (10):  105201.  DOI: 10.1088/1674-1056/ad6250 Abstract ( 62 )   HTML ( 0 )   PDF (1547KB) ( 52 )   The electrical parameters of H$_{2}$/Ar plasma in a cylindrical inductive discharge with an expansion region are investigated by a Langmuir probe, where Ar fractions range from 0% to 100%. The influence of gas composition and pressure on electron density, the effective electron temperature and the electron energy probability functions (EEPFs) at different spatial positions are present. In driver region, with the introduction of a small amount of Ar at 0.3 Pa, there is a rapid increase in electron density accompanied by a decrease in the effective electron temperature. Additionally, the shape of the EEPF transitions from a three-temperature distribution to a bi-Maxwellian distribution due to an increase in electron-electron collision. However, this phenomenon resulting from the changes in gas composition vanishes at 5 Pa due to the prior depletion of energetic electrons caused by the increase in pressure during hydrogen discharge. The EEPFs for the total energy in expansion region is coincident to these in the driver region at 0.3 Pa, as do the patterns of electron density variation between these two regions for differing Ar fractions. At 5 Pa, as the discharge transitions from H$_{2}$ to Ar, the EEPFs evolved from a bi-Maxwellian distribution with pronounced low energy electrons to a Maxwellian distribution in expansion region. This evolve may be attributed to a reduction in molecular vibrational excitation reactions of electrons during transport and the transition from localized electron dynamics in hydrogen discharge to non-localized electron dynamics in argon discharge. In order to validate the experimental results, we use the COMSOL simulation software to calculate electrical parameters under the same conditions. The evolution and spatial distribution of the electrical parameters of the simulation results agree well with the trend of the experimental results.

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Effect of matrix thermal properties on laser-induced plasma Yuheng Shan(单宇恒), An Li(李安), Xinyu Zhang(张新宇), Wen Yi(易文), Ying Zhang(张颖), Xiaodong Liu(刘晓东), and Ruibin Liu(刘瑞斌) Chin. Phys. B, 2024, 33 (10):  105202.  DOI: 10.1088/1674-1056/ad6251 Abstract ( 72 )   HTML ( 0 )   PDF (683KB) ( 44 )   The matrix thermal properties have an important impact on laser-induced plasma, as the thermal effect dominates the interaction between ns-pulsed laser and matter, especially in metals. We used a series of pure metals and aluminum alloys to measure plasma temperature and electron density through laser-induced breakdown spectroscopy, in order to investigate the effect of matrix thermal properties on laser-induced plasma. In pure metals, a significant negative linear correlation was observed between the matrix thermal storage coefficient and plasma temperature, while a weak correlation was observed with electron density. The results indicate that metals with low thermal conductivity or specific heat capacity require less laser energy for thermal diffusion or melting and evaporation, resulting in higher ablation rates and higher plasma temperatures. However, considering ionization energy, thermal effects may be a secondary factor affecting electron density. The experiment of aluminum alloy further confirms the influence of thermal conductivity on plasma temperature and its mechanism explanation.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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Direct observation of shock-induced phase transformation in polycrystalline iron via in situ x-ray diffraction Fan Zhang(张帆), Jia-Qin Dong(董佳钦), Zhi-Yong Xie(谢志勇), Zhi-Yu He(贺芝宇), Hua Shu(舒桦), Rui-Rong Wang(王瑞荣), Jun Xiong(熊俊), Guo Jia(贾果), Zhi-Heng Fang(方智恒), Wei Wang(王伟), Da-Wu Xiao(肖大武), An-Le Lei(雷安乐), Jie Chen(陈洁), and Xiu-Guang Huang(黄秀光) Chin. Phys. B, 2024, 33 (10):  106101.  DOI: 10.1088/1674-1056/ad625a Abstract ( 51 )   HTML ( 0 )   PDF (1412KB) ( 67 )   Phase transition of polycrystalline iron compressed along the Hugoniot is studied by combining laser-driven shock with in situ x-ray diffraction technique. It is suggested that polycrystalline iron changes from an initial body-centered cubic structure to a hexagonal close-packed structure with increasing pressure (i.e., a phase transition from $\alpha$ to $\varepsilon$). The relationship between density and pressure for polycrystalline iron obtained from the present experiments is found to be in good agreement with the gas-gun Hugoniot data. Our results show that experiments with samples at lower temperatures under static loading, such as in a diamond anvil cell, lead to higher densities measured than those found under dynamic loading. This means that extrapolating results of static experiments may not predict the dynamic responses of materials accurately. In addition, neither the face-centered cubic structure seen in previous molecular-dynamics simulations or two-phase coexistence are found within our experimental pressure range.

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Thermal conductivity of iron under the Earth's inner core pressure Cui-E Hu(胡翠娥), Mu-Xin Jiao(焦亩鑫), Xue-Nan Yang(杨学楠), Zhao-Yi Zeng(曾召益), and Jun Chen(陈军) Chin. Phys. B, 2024, 33 (10):  106501.  DOI: 10.1088/1674-1056/ad6078 Abstract ( 69 )   HTML ( 0 )   PDF (5736KB) ( 21 )   The thermal conductivity of $\varepsilon $-iron at high pressure and high temperature is a key parameter to constrain the dynamics and thermal evolution of the Earth's core. In this work, we use first-principles calculations to study the Hugoniot sound velocity and the thermal transport properties of $\varepsilon $-iron. The total thermal conductivity considering lattice vibration is 200 W/mK at the Earth's inner core conditions. The suppressed anharmonic interactions can significantly enhance the lattice thermal conductivity under high pressure, and the contribution of the lattice thermal conductivity should not be ignored under the Earth's core conditions.

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

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Optimized numerical density functional theory calculation of rotationally symmetric jellium model systems Guangdi Zhang(张广迪), Li Mao(毛力), and Hongxing Xu(徐红星) Chin. Phys. B, 2024, 33 (10):  107101.  DOI: 10.1088/1674-1056/ad655a Abstract ( 51 )   HTML ( 0 )   PDF (925KB) ( 55 )   In real space density functional theory calculations, the effective potential depends on the electron density, requiring self-consistent iterations, and numerous integrals at each step, making the process time-consuming. In our research, we propose an optimization method to expedite density functional theory (DFT) calculations for systems with large aspect ratios, such as metallic nanorods, nanowires, or scanning tunneling microscope tips. This method focuses on employing basis set to expand the electron density, Coulomb potential, and exchange-correlation potential. By precomputing integrals and caching redundant results, this expansion streamlines the integration process, significantly accelerating DFT computations. As a case study, we have applied this optimization to metallic nanorod systems of various radii and lengths, obtaining corresponding ground-state electron densities and potentials.

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The de Haas-van Alphen quantum oscillations in the kagome metal RbTi3Bi5 Zixian Dong(董自仙), Lei Shi(石磊), Bin Wang(王彬), Mengwu Huo(霍梦五), Xing Huang(黄星), Chaoxin Huang(黄潮欣), Peiyue Ma(马培跃), Yunwei Zhang(张云蔚), Bing Shen(沈冰), and Meng Wang(王猛) Chin. Phys. B, 2024, 33 (10):  107102.  DOI: 10.1088/1674-1056/ad6a0a Abstract ( 101 )   HTML ( 0 )   PDF (1374KB) ( 97 )   The kagome system has attracted great interest in condensed matter physics due to its unique structure that can host various exotic states such as superconductivity (SC), charge density waves (CDWs) and nontrivial topological states. The topological semimetal RbTi$_{3}$Bi$_{5}$ consisting of a Ti kagome layer shares a similar crystal structure to the topological correlated materials $A$V$_{3}$Sb$_{5}$ ($A = {\rm K}$, Rb, Cs) but without the absence of CDW and SC. Systematic de Haas-van Alphen oscillation measurements are performed on single crystals of RbTi$_{3}$Bi$_{5}$ to pursue nontrivial topological physics and exotic states. Combining this with theoretical calculations, the detailed Fermi surface topology and band structure are investigated. A two-dimensional Fermi pocket $\beta $ is revealed with a light effective mass, consistent with the semimetal predictions. The Landau fan diagram of RbTi$_{3}$Bi$_{5}$ reveals a zero Berry phase for the $\beta $ oscillation in contrast to that of CsTi$_{3}$Bi$_{5}$. These results suggest that kagome RbTi$_{3}$Bi$_{5 }$ is a good candidate for exploring nontrivial topological exotic states and topological correlated physics.

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Phase induced localization transition Tong Liu(刘通), Xingbo Wei(魏兴波), and Youguo Wang(王友国) Chin. Phys. B, 2024, 33 (10):  107103.  DOI: 10.1088/1674-1056/ad6a0b Abstract ( 67 )   HTML ( 1 )   PDF (854KB) ( 81 )   Localization phenomenon is an important research field in condensed matter physics. However, due to the complexity and subtlety of disordered systems, new localization phenomena always emerge unexpectedly. For example, it is generally believed that the phase of the hopping term does not affect the localization properties of the system, so the calculation of the phase is often ignored in the study of localization. Here, we introduce a quasiperiodic model and demonstrate that the phase change of the hopping term can significantly alter the localization properties of the system through detailed numerical simulations, such as the inverse participation ratio and multifractal analysis. This phase-induced localization transition provides valuable information for the study of localization physics.

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Strain tunable excitonic optical properties in monolayer Ga2O3 Hao-Lei Cui(崔浩磊), Zhen Quan(权真), and Shu-Dong Wang(王舒东) Chin. Phys. B, 2024, 33 (10):  107104.  DOI: 10.1088/1674-1056/ad74e7 Abstract ( 57 )   HTML ( 0 )   PDF (3093KB) ( 15 )   Two-dimensional (2D) Ga$_{2}$O$_{3}$ has been confirmed to be a stable structure with five atomic layer thickness configuration. In this work, we study the quasi-particle electronic band structures and then access the excitonic optical properties through solving the Bethe-Salpeter equation (BSE). The results reveal that the exciton dominates the optical absorption in the visible light region with the binding energy as large as $\sim 1.0$ eV, which is highly stable at room temperature. Importantly, both the dominant absorption P$_{1}$ and P$_{2}$ peaks are optically bright without dark exciton between them, and thus is favorable for luminescence process. The calculated radiative lifetime of the lowest-energy exciton is 2.0$\times10^{-11}$ s at 0 K. Furthermore, the radiative lifetime under $+4$% tensile strain is one order of magnitude shorter than that of the strain-free case, while it is less insensitive under the compressive strain. Our findings set the stage for future theoretical and experimental investigation on monolayer Ga$_{2}$O$_{3}$.

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Excitonic optical properties in monolayer SnP2S6 Peng-Yuan Chen(陈鹏远), Zhen Quan(权真), and Shu-Dong Wang(王舒东) Chin. Phys. B, 2024, 33 (10):  107105.  DOI: 10.1088/1674-1056/ad73b5 Abstract ( 88 )   HTML ( 1 )   PDF (792KB) ( 95 )   Quantum confinement effect and reduced dielectric screening in two-dimensional (2D) dramatically enhance the electron-hole interactions. In this work, we use many-body perturbation theory and Bethe-Salpeter equation (BSE) to investigate the electronic and excitonic optical properties of monolayer SnP$_{2}$S$_{6}$. Our findings reveal that the excitonic effect dominates the optical absorption spectra in the visible light range, and the lowest-energy exciton $X_{0}$ in monolayer SnP$_{2}$S$_{6}$ is optically bright with the binding energy of 0.87 eV and the radiative lifetime of $\sim 10^{-11}$ s, which is highly advantageous to the photo-luminescence. Most importantly, the absence of optically forbidden states below the bright states $X_{0}$ would give rise to a high quantum efficiency of 2D SnP$_{2}$S$_{6}$. We also find that applied biaxial strain can further shorten the radiative lifetime of the bright states. These results imply that 2D SnP$_{2}$S$_{6}$ is a promising candidate for the optoelectronic devices.

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Peak structure in the interlayer conductance of Moiré superlattices Yizhou Tao(陶懿洲), Chao Liu(刘超), Mingwen Xiao(肖明文), and Henan Fang(方贺男) Chin. Phys. B, 2024, 33 (10):  107301.  DOI: 10.1088/1674-1056/ad655b Abstract ( 62 )   HTML ( 1 )   PDF (726KB) ( 25 )   We investigate the peak structure in the interlayer conductance of Moiré superlattices using a tunneling theory we developed previously. The theoretical results predict that, due to the resonance of two different partial waves, the double-peak structure can appear in the curve of the interlayer conductance versus twist angle. Furthermore, we study the influences of the model parameters, i.e., the chemical potential of electrodes, the thickness of Moiré superlattice, and the strength of interface potential, on the peak structure of the interlayer conductance. In particular, the parameter dependence of the peak structure is concluded via a phase diagram, and the physical meanings of the phase diagram is formulized. Finally, the potential applications of the present work is discussed.

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Edge modes in finite-size systems with different edge terminals Huiping Wang(王会平), Li Ren(任莉), Xiuli Zhang(张修丽), and Liguo Qin(秦立国) Chin. Phys. B, 2024, 33 (10):  107302.  DOI: 10.1088/1674-1056/ad6a05 Abstract ( 55 )   HTML ( 0 )   PDF (2029KB) ( 5 )   We investigate the behavior of edge modes in the presence of different edge terminations and long-range (LR) hopping. Here, we mainly focus on such model crystals with two different types of structures (type I: "$\cdots $-$P$-$Q$-$P$-$Q$-$\cdots $" and type II: "$\cdots=P$-$Q=P$-$Q=\cdots$"), where $P$ and $Q$ represent crystal lines (CLs), while the symbols "$-$" and "$=$" denote the distance between the nearest neighbor (NN) CLs. Based on the lattice model Hamiltonian with LR hopping, the existence of edge modes is determined analytically by using the transfer matrix method (TMM) when different edge terminals are taken into consideration. Our findings are consistent with the numerical results obtained by the exact diagonalization method. We also notice that edge modes can exhibit different behaviors under different edge terminals. Our result is helpful in solving novel edge modes in honeycomb crystalline graphene and transition metal dichalcogenides with different edge terminals.

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Prediction of novel layered indium halide superconductors Zhi-Hong Yuan(袁志红), Jing-Jing Meng(孟静静), Rui Liu(刘瑞), Peng-Yu Zheng(郑鹏宇), and Zhi-Ping Yin(殷志平) Chin. Phys. B, 2024, 33 (10):  107401.  DOI: 10.1088/1674-1056/ad6a09 Abstract ( 85 )   HTML ( 0 )   PDF (4202KB) ( 90 )   We design two new layered indium halide compounds LaOInF$_{2}$ and LaOInCl$_{2}$ by means of first-principles calculations and evolutionary crystal structure prediction. We find both compounds crystallize in a tetragonal structure with $P4/nmm$ space group and have indirect band gaps of 2.58 eV and 3.21 eV, respectively. By substituting O with F, both of them become metallic and superconducting at low temperature. The F-doping leads to strong electron-phonon coupling in the low-energy acoustic phonon modes which is mainly responsible for the induced superconductivity. The total electron-phonon coupling strength are 1.86 and 1.48, while the superconducting transition temperature ($T_{\rm c}$) are about 7.2 K and 6.5 K with 10% and 5% F doping for LaOInF$_{2}$ and LaOInCl$_{2}$, respectively.

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Spin-orbit torque effect in silicon-based sputtered Mn3Sn film Sha Lu(卢莎), Dequan Meng(孟德全), Adnan Khan, Ziao Wang(王子傲), Shiwei Chen(陈是位), and Shiheng Liang(梁世恒) Chin. Phys. B, 2024, 33 (10):  107501.  DOI: 10.1088/1674-1056/ad6079 Abstract ( 71 )   HTML ( 0 )   PDF (1398KB) ( 72 )   Noncollinear antiferromagnet Mn$_{3}$Sn has shown remarkable efficiency in charge-spin conversion, a novel magnetic spin Hall effect, and a stable topological antiferromagnetic state, which has resulted in great interest from researchers in the field of spin-orbit torque. Current research has primarily focused on the spin-orbit torque effect of epitaxially grown noncollinear antiferromagnet Mn$_{3}$Sn films. However, this method is not suitable for large-scale industrial preparation. In this study, amorphous Mn$_{3}$Sn films and Mn$_{3}$Sn/Py heterostructures were prepared using magnetron sputtering on silicon substrates. The spin-torque ferromagnetic resonance measurement demonstrated that only the conventional spin-orbit torque effect generated by in-plane polarized spin currents existed in the Mn$_{3}$Sn/Py heterostructure, with a spin-orbit torque efficiency of 0.016. Additionally, we prepared the perpendicular magnetized Mn$_{3}$Sn/CoTb heterostructure based on amorphous Mn$_{3}$Sn film, where the spin-orbit torque driven perpendicular magnetization switching was achieved with a lower critical switching current density (3.9$\times10^{7}$ A/cm$^{2})$ compared to Ta/CoTb heterostructure. This research reveals the spin-orbit torque effect of amorphous Mn$_{3}$Sn films and establishes a foundation for further advancement in the practical application of Mn$_{3}$Sn materials in spintronic devices.

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Polarity-controllable magnetic skyrmion filter Xiao-Lin Ai(艾啸林), Hui-Ting Li(李慧婷), Xue-Feng Zhang(张雪枫), Chang-Feng Li(李昌锋), Je-Ho Shim(沈帝虎), Xiao-Ping Ma(马晓萍), and Hong-Guang Piao(朴红光) Chin. Phys. B, 2024, 33 (10):  107502.  DOI: 10.1088/1674-1056/ad6421 Abstract ( 56 )   HTML ( 0 )   PDF (1694KB) ( 34 )   The skyrmion generator is one of the indispensable components for the future functional skyrmion devices, but the process of generating skyrmion cannot avoid mixing with other magnetic textures, such as skyrmionium and nested skyrmion bags. These mixed magnetic textures will inevitably lead to the blockage of skyrmion transport and even the distortion of data information. Therefore, the design of an efficient skyrmion filter is of great significance for the development of skyrmion-based spintronic devices. In this work, a skyrmion filter scheme is proposed, and the high-efficiency filtering function is demonstrated by micromagnetic simulations. The results show that the filtering effect of the scheme depends on the structure geometry and the spin current density that drives the skyrmion. Based on this scheme, the polarity of the filtered skyrmion can be controlled by switching the magnetization state at the output end, and the "cloning" of the skyrmion can be realized by geometric optimization of the structure. We believe that in the near future, the skyrmion filter will become one of the important components of skyrmion-based spintronic devices in the future.

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Enhanced soft magnetic properties of SiO2-coated FeSiCr magnetic powder cores by particle size effect Mingyue Ge(葛铭悦), Likang Xiao(肖礼康), Xiaoru Liu(刘潇如), Lin Pan(潘嶙), Zhangyang Zhou(周章洋), Jianghe Lan(蓝江河), Zhengwei Xiong(熊政伟), Jichuan Wu(吴冀川), and Zhipeng Gao(高志鹏) Chin. Phys. B, 2024, 33 (10):  107503.  DOI: 10.1088/1674-1056/ad6556 Abstract ( 67 )   HTML ( 0 )   PDF (1553KB) ( 88 )   It has been known that metal FeSiCr powders with large average particle sizes have been typically employed to prepare magnetic powder cores (SMCs), with few studies reported on the influence of magnetic properties for original powders with various average particle sizes less than 10 μm. In this work, SiO$_{2}$-coated FeSiCr SMCs with different small particle sizes were synthesized using the sol-gel process. The contribution of SiO$_{2}$ coating amount and voids to the soft magnetic properties was elaborated. The mechanism was revealed such that smaller particle sizes with less voids could be beneficial for reducing core loss in the SMCs. By optimizing the core structure, permeability and magnetic loss of 26 and 262 kW/cm$^{3}$ at 100 kHz and 50 mT were achieved at a particle size of 4.8 μm and ethyl orthosilicate addition of 0.1 mL/g. The best DC stacking performance, reaching 87%, was observed at an ethyl orthosilicate addition rate of 0.25 mL/g under 100 Oe. Compared to other soft magnetic composites (SMCs), the FeSiCr/SiO$_{2}$ SMCs exhibit significantly reduced magnetic loss. It further reduces the magnetic loss of the powder core, providing a new strategy for applications of SMCs at high frequencies.

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Skyrmion motion induced by spin-waves on magnetic nanotubes Tijjani Abdulrazak, Xuejuan Liu(刘雪娟), Zhenyu Wang(王振宇), Yunshan Cao(曹云姗), and Peng Yan(严鹏) Chin. Phys. B, 2024, 33 (10):  107504.  DOI: 10.1088/1674-1056/ad5d64 Abstract ( 56 )   HTML ( 0 )   PDF (883KB) ( 13 )   We investigate the skyrmion motion driven by spin waves on magnetic nanotubes through micromagnetic simulations. Our key results include demonstrating the stability and enhanced mobility of skyrmions on the edgeless nanotube geometry, which prevents destruction at boundaries - a common issue in planar geometries. We explore the influence of the damping coefficient, amplitude, and frequency of microwaves on skyrmion dynamics, revealing a non-uniform velocity profile characterized by acceleration and deceleration phases. Our results show that the skyrmion Hall effect is significantly modulated on nanotubes compared to planar models, with specific dependencies on the spin-wave parameters. These findings provide insights into skyrmion manipulation for spintronic applications, highlighting the potential for high-speed and efficient information transport in magnonic devices.

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Low Gilbert damping in Bi/In-doped YIG thin films with giant Faraday effect Jin Zhan(湛劲), Yi Wang(王一), Xianjie Wang(王先杰), Hanxu Zhang(张晗旭), Senyin Zhu(朱森寅), Lingli Zhang(张伶莉), Lingling Tao(陶玲玲), Yu Sui(隋郁), Wenqing He(何文卿), Caihua Wan(万蔡华), Xiufeng Han(韩秀峰), V. I. Belotelov, and Bo Song(宋波) Chin. Phys. B, 2024, 33 (10):  107505.  DOI: 10.1088/1674-1056/ad6b84 Abstract ( 103 )   HTML ( 1 )   PDF (1126KB) ( 79 )   Magnetic films with low Gilbert damping are crucial for magnonic devices, which provide a promising platform for realizing ultralow-energy devices. In this study, low Gilbert damping and coercive field were observed in Bi/In-doped yttrium iron garnet (BiIn:YIG) thin films. The BiIn:YIG (444) films were deposited onto different substrates using pulsed laser deposition. Low coercivity ($<$1 Oe) with saturation magnetization of 125.09 emu/cc was achieved along the in-plane direction of BiIn:YIG film. The values of Gilbert damping and inhomogeneous broadening of ferromagnetic resonance in BiIn:YIG films were obtained to be as low as $4.05\times 10^{-4}$ and 5.62 Oe, respectively. In addition to low damping, the giant Faraday rotation angles (up to $2.9\times 10^{4}$ deg/cm) were also observed in the BiIn:YIG film. By modifying the magnetic structure and coupling effect between Bi$^{3+}$ and Fe$^{3+}$ of Bi:YIG, doped In$^{3+}$ plays a key role on variation of the magnetic properties. The low damping and giant Faraday effect made the BiIn:YIG film an appealing candidate for magnonic and magneto-optical devices.

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Impact of Co2+ substitution on structure and magnetic properties of M-type strontium ferrite with different Fe/Sr ratios Yang Sun(孙洋), Ruoshui Liu(刘若水), Huayang Gong(宫华扬), and Baogen Shen(沈保根) Chin. Phys. B, 2024, 33 (10):  107506.  DOI: 10.1088/1674-1056/ad6554 Abstract ( 75 )   HTML ( 0 )   PDF (2035KB) ( 30 )   Ion substitution has significantly improved the performance of ferrite magnets, and cobalt remains a key area of research. Studies on the mechanism of Co$^{2+}$ in strontium ferrite, especially SrFe$_{2n-x}$Co$_{x}$O$_{19-\delta }$ ($n = 6.1$-5.4; $x = 0.05$-0.20) synthesized using the ceramic method, showed that Co$^{2+}$ preferentially enters the lattice as the Fe/Sr ratio decreases. This results in a decrease in the lattice constants $a$ and $c$ due to oxygen vacancies and iron ion deficiency. The impact of Co substitution on morphology is minor compared to the effect of the Fe/Sr ratio. As the Fe/Sr ratio decreases and the Co content increases, the saturation magnetization decreases. The magnetic anisotropy field exhibits a nonlinear change, generally increasing with higher Fe/Sr ratios and Co content. These changes in the performance of permanent magnets are attributed to the absence of Fe$^{3+}$ ions at the $12k + 2a$ and 2$b$ sites and the substitution of Co$^{2+}$ at the 2$b$ site. This suggests that by adjusting the Fe/Sr ratio and appropriate Co substitution, the magnetic anisotropy field of M-type strontium ferrite can be effectively optimized.

INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY

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The B-site ordering in RFe0.5Cr0.5O3 ceramics and its effect on magnetic properties Li Hou(侯利), Lei Shi(石磊), Liping Yang(杨利平), Yiqiang Liu(刘义强), Zhitao Li(李志涛), and Lanxiang Meng(孟蓝翔) Chin. Phys. B, 2024, 33 (10):  108101.  DOI: 10.1088/1674-1056/ad641e Abstract ( 59 )   HTML ( 0 )   PDF (2716KB) ( 10 )   To insight into the B-site ordering in $R$Fe$_{0.5}$Cr$_{0.5}$O$_{3}$ ceramics, a series of $R$Fe$_{0.5}$Cr$_{0.5}$O$_{3}$ ceramics ($R={\rm La}$, Y, Lu) were synthesized by the sol-gel method, and the structural and magnetic properties were systemically investigated. By using the Rietveld refinement of all samples, it is found that the structural distortion is increased as the $R$ ionic radius decreases, leading to the weakened interactions between Fe/Cr ions. Moreover, the Fe and Cr are arranged in disorder in LaFe$_{0.5}$Cr$_{0.5}$O$_{3}$, but partially ordered in YFe$_{0.5}$Cr$_{0.5}$O$_{3}$ and LuFe$_{0.5}$Cr$_{0.5}$O$_{3}$, showing an increasing trend of the proportion of ordered domains with the decrease of $R$ ionic radius. Through fitting the temperature-dependent magnetizations, it is identified that the magnetization reversal (MR) in disorder LaFe$_{0.5}$Cr$_{0.5}$O$_{3}$ is resulted from the competition between the moments of Cr and Fe sublattices. In the partially ordered YFe$_{0.5}$Cr$_{0.5}$O$_{3}$ and LuFe$_{0.5}$Cr$_{0.5}$O$_{3}$ ceramics, because of the presence of Fe-O-Cr networks in the ordered domains whose moment is antiparallel to that of Fe-O-Fe and Cr-O-Cr in the disordered domains, the compensation temperature $T_{\rm comp}$ of MR is increased by nearly 50 K. These results suggest that the changing of $R$-site ions could be used very effectively to modify the Fe-O-Cr ordering, apart from the structural distortion, which has a direct effect on the magnetic exchange interactions in $R$Fe$_{0.5}$Cr$_{0.5}$O$_{3}$ ceramics. Then at values of composition where ordered domains are expected to be larger in number as compared to disordered domains and with a weaker structural distortion, one can expect a higher transition temperature $T_{\rm comp}$, providing a different view for adjustment of the magnetic properties of $R$Fe$_{0.5}$Cr$_{0.5}$O$_{3}$ ceramics for practical applications.

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Exploring negative ion behaviors and their influence on properties of DC magnetron sputtered ITO films under varied power and pressure conditions Maoyang Li(李茂洋), Chaochao Mo(莫超超), Peiyu Ji(季佩宇), Xiaoman Zhang(张潇漫), Jiali Chen(陈佳丽), Lanjian Zhuge(诸葛兰剑), Xuemei Wu(吴雪梅), Haiyun Tan(谭海云), and Tianyuan Huang(黄天源) Chin. Phys. B, 2024, 33 (10):  108102.  DOI: 10.1088/1674-1056/ad62df Abstract ( 62 )   HTML ( 0 )   PDF (1434KB) ( 69 )   We deposited indium-tin-oxide (ITO) films on silicon and quartz substrates by magnetron sputtering technology in pure argon. Using electrostatic quadrupole plasma diagnostic technology, we investigate the effects of discharge power and discharge pressure on the ion flux and energy distribution function of incidence on the substrate surface, with special attention to the production of high-energy negative oxygen ions, and elucidate the mechanism behind its production. At the same time, the structure and properties of ITO films are systematically characterized to understand the potential effects of high energy oxygen ions on the growth of ITO films. Combining with the kinetic property analysis of sputtering damage mechanism of transparent conductive oxide (TCO) thin films, this study provides valuable physical understanding of optimization of TCO thin film deposition process.

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Recension of boron nitride phase diagram based on high-pressure and high-temperature experiments Ruike Zhang(张瑞柯), Ruiang Guo(郭睿昂), Qian Li(李倩), Shuaiqi Li(李帅琦), Haidong Long(龙海东), and Duanwei He(贺端威) Chin. Phys. B, 2024, 33 (10):  108103.  DOI: 10.1088/1674-1056/ad6a06 Abstract ( 62 )   HTML ( 0 )   PDF (2933KB) ( 21 )   Cubic boron nitride and hexagonal boron nitride are the two predominant crystalline structures of boron nitride. They can interconvert under varying pressure and temperature conditions. However, this transformation requires overcoming significant potential barriers in dynamics, which poses great difficulty in determining the c-BN/h-BN phase boundary. This study used high-pressure in situ differential thermal measurements to ascertain the temperature of h-BN/c-BN conversion within the commonly used pressure range (3-6 GPa) for the industrial synthesis of c-BN to constrain the $P$-$T$ phase boundary of h-BN/c-BN in the pressure-temperature range as much as possible. Based on the analysis of the experimental data, it is determined that the relationship between pressure and temperature conforms to the following equation: $P = a + \frac{1}{b}T$. Here, $P$ denotes the pressure (GPa) and $T$ is the temperature (K). The coefficients are $a = -3.8\pm0.8$ GPa and $b = 229.8\pm17.1$ GPa/K. These findings call into question existing high-pressure and high-temperature phase diagrams of boron nitride, which seem to overstate the phase boundary temperature between c-BN and h-BN. The BN phase diagram obtained from this study can provide critical temperature and pressure condition guidance for the industrial synthesis of c-BN, thus optimizing synthesis efficiency and product performance.

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Study of leakage current degradation based on stacking faults expansion in irradiated SiC junction barrier Schottky diodes Maojiu Luo(罗茂久), Yourun Zhang(张有润), Yucheng Wang(王煜丞), Hang Chen(陈航), Rong Zhou(周嵘), Zhi Wang(王智), Chao Lu(陆超), and Bo Zhang(张波) Chin. Phys. B, 2024, 33 (10):  108401.  DOI: 10.1088/1674-1056/ad6255 Abstract ( 76 )   HTML ( 1 )   PDF (1372KB) ( 22 )   A comprehensive investigation was conducted to explore the degradation mechanism of leakage current in SiC junction barrier Schottky (JBS) diodes under heavy ion irradiation. We propose and verify that the generation of stacking faults (SFs) induced by the recombination of massive electron-hole pairs during irradiation is the cause of reverse leakage current degradation based on experiments results. The irradiation experiment was carried out based on Ta ions with high linear energy transfer (LET) of 90.5 MeV/(mg/cm$^{2}$). It is observed that the leakage current of the diode undergoes the permanent increase during irradiation when biased at 20% of the rated reverse voltage. Micro-PL spectroscopy and PL micro-imaging were utilized to detect the presence of SFs in the irradiated SiC JBS diodes. We combined the degraded performance of irradiated samples with SFs introduced by heavy ion irradiation. Finally, three-dimensional (3D) TCAD simulation was employed to evaluate the excessive electron-hole pairs (EHPs) concentration excited by heavy ion irradiation. It was observed that the excessive hole concentration under irradiation exceeded significantly the threshold hole concentration necessary for the expansion of SFs in the substrate. The proposed mechanism suggests that the process and material characteristics of the silicon carbide should be considered in order to reinforcing against the single event effect of SiC power devices.

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Membrane tension evolution and mechanical regulation of melittin-induced membrane poration Wanting Zhang(张婉婷), Rong Xu(徐榕), Wendong Ma(马文东), Zhao Lin(林召), Kai Yang(杨恺), and Bing Yuan(元冰) Chin. Phys. B, 2024, 33 (10):  108701.  DOI: 10.1088/1674-1056/ad6254 Abstract ( 65 )   HTML ( 0 )   PDF (1946KB) ( 95 )   Membrane tension plays a crucial role in various fundamental cellular processes, with one notable example being the T cell-mediated elimination of tumor cells through perforin-induced membrane perforation by amplifying cellular force. However, the mechanisms governing the regulation of biomolecular activities at the cell interface by membrane tension remain elusive. In this study, we investigated the correlation between membrane tension and poration activity of melittin, a prototypical pore-forming peptide, using dynamic giant unilamellar vesicle leakage assays combined with flickering tension analysis, molecular dynamics simulations, and live cell assays. The results demonstrate that an increase in membrane tension enhances the activity of melittin, particularly near its critical pore-forming concentration. Moreover, peptide actions such as binding, insertion, and aggregation in the membrane further influence the evolution of membrane tension. Live cell experiments reveal that artificially enhancing membrane tension effectively enhances melittin's ability to induce pore formation and disrupt membranes, resulting in up to a ten-fold increase in A549 cell mortality when exposed to a concentration of 2.0-μg$\cdot$mL$^{-1}$ melittin. Our findings elucidate the relationship between membrane tension and the mechanism of action as well as pore-forming efficiency of melittin, while providing a practical mechanical approach for regulating functional activity of molecules at the cell-membrane interface.