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30 October 2025, Volume 34 Issue 11 Previous issue    Next issue

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SPECIAL TOPIC — Heat conduction and its related interdisciplinary areas

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Strain modulated phonon transport in one-dimensional nonlinear lattice with on-site potential Hongbin Chen(陈宏斌), Nianbei Li(李念北), and Jie Chen(陈杰) Chin. Phys. B, 2025, 34 (11):  114401.  DOI: 10.1088/1674-1056/adf1ea Abstract ( 24 )   HTML ( 0 )   PDF (598KB) ( 8 )   The one-dimensional (1D) nonlinear lattices with on-site potentials exhibit normal heat conduction and energy diffusion behaviors. The strain-modulated energy diffusion constants are studied for the 1D Frenkel-Kontorova (FK) lattices, which are typical lattices with on-site potentials. The 1D FK lattices show strain-modulated symmetric behaviors of local extrema in energy diffusion constants, similar to those previously observed in 1D Fermi-Pasta-Ulam (FPU) lattices that contain only interparticle potentials. However, the 1D FK lattices exhibit local minima in energy diffusion constants, which is in contrast to the behavior of the 1D FPU lattices. Although strain always enhances the phonon group velocity and suppresses the phonon relaxation time for both the 1D FK and FPU lattices, the suppression of the phonon relaxation time is much weaker for the 1D FK lattices compared to the 1D FPU lattices.

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Thermal diode with switchable cloaking effect enabled by asymmetric temperature-dependent thermal conductivity Mengzhen Xue(薛梦贞), Jun Wang(王军), and Guodong Xia(夏国栋) Chin. Phys. B, 2025, 34 (11):  114403.  DOI: 10.1088/1674-1056/ae118b Abstract ( 24 )   HTML ( 0 )   PDF (1188KB) ( 6 )   Thermal rectification refers to the asymmetry in heat transfer capability when subjected to forward and reverse temperature gradients. A thermal cloak can render objects invisible in thermal fields by redirecting heat flux pathways. In this paper, we present a thermal diode model based on a bi-layer thermal cloak system that incorporates a composite heat-flux-attracting layer with asymmetric, temperature-dependent thermal conductivity. In the forward case, the heat flux bypasses the cloaking region while maintaining undistorted background isotherm contours, whereas in the reverse case, the thermal cloak fails to function and the device effectively insulates heat. Consequently, thermal rectification occurs in the bi-layer thermal cloak system. A significant increase in the thermal rectification ratio is observed as the temperature gradient increases. By optimizing the system dimensions, a peak rectification ratio of 11.06 is achieved. This study provides physical insight and a design framework for developing novel thermal diodes with dual-functional thermal management capabilities.

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A molecular dynamics study of bubble nucleation on grooved surfaces: Effects of wettability and heat flux Mian Yu(余绵), Bingheng Li(李丙衡), Lianfeng Wu(吴连锋), Lianxiang Ma(马连湘), Xiangwen Meng(孟祥文), and Yuanzheng Tang(唐元政) Chin. Phys. B, 2025, 34 (11):  114703.  DOI: 10.1088/1674-1056/ae0896 Abstract ( 39 )   HTML ( 0 )   PDF (2302KB) ( 2 )   Bubble nucleation plays a crucial role in boiling heat transfer and other applications. Traditional experiments struggle to capture its microscopic mechanisms, making molecular dynamics simulations a powerful tool for such studies. This work uses molecular dynamics simulations to investigate bubble nucleation of water on copper surfaces with sinusoidal groove roughness under varying heat flux and surface wettability. Results show that at the same wettability, higher heat flux leads to higher surface temperatures after the same heating time, promoting bubble nucleation, growth, and departure. Moreover, under constant heat flux, stronger surface hydrophilicity enhances heat transfer from the solid to the liquid, further accelerating the nucleation. This study provides valuable insights into the mechanism of bubble nucleation and offers theoretical guidance for enhancing heat transfer.

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Molecular dynamics study incorporating regression analysis: Quantitative effects of sinusoidal protrusions and wettability on water phase transition containing insoluble gases Bingheng Li(李丙衡), Yujian Gao(高雨键), Mian Yu(余绵), Lianfeng Wu(吴连锋), Lianxiang Ma(马连湘), and Yuanzheng Tang(唐元政) Chin. Phys. B, 2025, 34 (11):  114704.  DOI: 10.1088/1674-1056/ae0894 Abstract ( 22 )   HTML ( 0 )   PDF (2249KB) ( 3 )   Molecular dynamics simulations were employed to establish a more realistic model of nanoscale boiling phase transitions. We examined the effects of different configurations of nanoscale sinusoidal protrusions and surface wettability on the phase transition behavior of systems containing insoluble gases under continuous heat flux input. To enhance the clarity and comparability of the results, a quantitative evaluation method was introduced. The findings reveal that, under identical wettability conditions, increasing the number of sinusoidal protrusions accelerates the onset of phase transition. In contrast, for a fixed number of protrusions, higher surface wettability delays the initiation of the phase change. By incorporating regression analysis to quantify the phase transition process and compare influencing factors, it was observed that although high wettability generally inhibits phase transition, the synergistic interaction between surface structure and wettability ultimately facilitates the phase transition process.

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Efficient thermal rectification in nitrogen-doped carbon nanotube heterostructures Zhibo Xing(邢志博), Yingguang Liu(刘英光), Haochen Liu(刘浩宸), Yahao Wang(王雅浩), Cheng Zhang(张成), and Ning Wu(吴宁) Chin. Phys. B, 2025, 34 (11):  116101.  DOI: 10.1088/1674-1056/adfdc4 Abstract ( 16 )   HTML ( 0 )   PDF (3070KB) ( 5 )   Carbon nanotubes (CNTs) are widely used in various fields owing to their unique properties. In this study, three different types of nitrogen-doped CNT heterojunctions were constructed: parallel-doped (PCNT), vertically doped (VCNT), and mesh-doped (MCNT). Non-equilibrium molecular dynamics (NEMD) simulations were conducted to investigate their heat flux and thermal rectification (TR) effects. The results show that heat flux preferentially flows from nitrogen-doped regions to undoped regions, exhibiting distinct thermal rectification behavior, with PCNT showing the most pronounced effect. Interestingly, the TR ratio of the zigzag PCNT is significantly higher than that of the armchair PCNT. Subsequently, we examined the effects of system length and diameter on the TR ratio of the PCNT and found that the TR ratio increases and then decreases with increasing model length. In addition, the effect of defect density on the heat flux of the PCNT is peculiar. The phonon density of states, phonon dispersion, participation ratio, and phonon spectral heat flux were analyzed to elucidate the thermal transport behavior of phonons in the nanotubes. This study provides insights into the development and design of nitrogen-doped CNT thermal rectifiers.

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Finite-size effects on phonon-mediated thermal transport across Si-Ge interfaces: Spectral analysis and parameter optimization for molecular dynamics simulations Zhicong Wei(魏志聪), Haoqiang Li(李浩强), Jianlian Huang(黄建廉), Weikuang Li(李唯宽), Yijuan Li(李艺娟), Yajuan Cheng(程亚娟), and Shiyun Xiong(熊世云) Chin. Phys. B, 2025, 34 (11):  116301.  DOI: 10.1088/1674-1056/ae0432 Abstract ( 22 )   HTML ( 0 )   PDF (2194KB) ( 11 )   The interfacial thermal resistance (ITR) at material interfaces has emerged as a critical factor in the thermal management of micro/nanoelectronic devices and composite materials. Using non-equilibrium molecular dynamics simulations, we systematically investigate how simulation parameters affect the calculated ITR in Si/Ge heterojunctions. Our results demonstrate that the ITR decreases with increasing system length $L_{\rm sys}$ and thermal bath length $L_{\rm bath}$. We identify linear relationships between ITR and the inverse of both $L_{\rm sys}$ and $L_{\rm bath}$, enabling reliable extrapolation to infinite-system values. While the thermostat coupling constant $\tau$ shows a negligible influence on ITR, excessively large values ($\tau > 5$ ps) compromise temperature control accuracy. Spectral analysis reveals that these size effects primarily originate from mid-to-low-frequency phonons (< 6 THz), whose long mean free paths make their transport particularly sensitive to system dimensions. This work establishes fundamental guidelines for parameter selection in interfacial thermal transport simulations, while providing new insights into phonon-interface interactions. The findings offer valuable implications for thermal design in high-power devices and composite materials, where accurate ITR prediction is crucial for performance optimization.

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Local time reversal symmetry breaking induced attenuation and localization of phonon transmission Yu-Jia Zeng(曾育佳), Qi-Zhuang Qu(曲其壮), Zhong-Ke Ding(丁中科), and Wu-Xing Zhou(周五星) Chin. Phys. B, 2025, 34 (11):  116302.  DOI: 10.1088/1674-1056/adf61b Abstract ( 28 )   HTML ( 0 )   PDF (7774KB) ( 4 )   Time-reversal symmetry (TRS) breaking induced dissipationless topological phonon edge modes provide an unprecedented way to manipulate phonon transport. However, the effect of TRS breaking on the transport properties of bulk phonon modes is still unclear. In this work, we assess the effect of local TRS-breaking domains on the transport properties of bulk phonon modes in a two-dimensional (2D) hexagonal phononic lattice model. The results show that bulk phonon modes can be strongly scattered by local TRS breaking owing to the shift of the local phonon band gap, which results in significant suppression of phonon transmission. Moreover, we show that the aperiodic distribution of local TRS-breaking domains can induce phonon Anderson localization, and the localization length can be effectively tuned by the strength of TRS breaking. Our study suggests that TRS breaking can not only be used to construct dissipationless topological phonon edge states, but also be used to block the transmission of bulk phonon modes by carefully controlling the size and distribution of TRS-breaking domains. Such results provide a highly alternative way for manipulating energy flux at the nanoscale.

SPECIAL TOPIC — Structures and properties of materials under high pressure

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Unconventional stabilization mechanisms and emergent superconductivity in scandium polychlorides under extreme conditions Ziji Shao(邵子霁), Maosheng Miao(苗茂生), Wendi Zhao(赵文迪), Mengxi Wang(王梦溪), Yingmei Zhu(朱英梅), Changqiu Yu(于长秋), Defang Duan(段德芳), and Tiejun Zhou(周铁军) Chin. Phys. B, 2025, 34 (11):  116201.  DOI: 10.1088/1674-1056/ae0431 Abstract ( 37 )   HTML ( 0 )   PDF (10146KB) ( 8 )   Using first-principles evolutionary crystal structure prediction, we systematically investigate scandium polychlorides across 50-300 GPa, predicting multiple thermodynamically stable phases ScCl, ScCl$_{2}$, ScCl$_{3}$, ScCl$_{5}$, and ScCl$_{7}$ with unconventional stoichiometries. The exceptional stability of these compounds stems from the mutually compatible crystal orbitals of the Sc and Cl sublattices, strong ionic interactions, and the formation of Cl-Cl homobonds. These factors play critical roles in stabilizing scandium chloride compounds with various unconventional stoichiometries. Notably high-pressure novel ScCl phases with $P$6$_{3}$/mmc and Pm-3$m$ symmetries can be metastable at ambient pressure upon decompression and convert into superconductive electrides. Pm-3-ScCl$_{7}$ exhibits significant pressure-modulated superconductivity, featuring an enhancement of $T_{\rm c}$ to 10.91 K at a low pressure of 75 GPa. In addition, the universal superconductivity found in the Pm-3 structured chlorides suggests a promising structural prototype for pressure-tunable superconductors.

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Structure and superconductivity of La2PrNi2O7 under pressure Qing Tian(田清), Denghui Zhu(朱登辉), and Wei Zhang(张微) Chin. Phys. B, 2025, 34 (11):  117101.  DOI: 10.1088/1674-1056/adfef6 Abstract ( 33 )   HTML ( 0 )   PDF (1717KB) ( 8 )   Nickel-based superconductors have attracted great attention due to the finding of the Ruddlesden-Popper (R-P) bilayer nickelate La$_{3}$Ni$_{2}$O$_{7}$ with superconducting critical temperature ($T_{\rm c}$) of 80 K at pressure above 14 GPa. Recent efforts have been devoted to the study of La$_{2}$PrNi$_{2}$O$_{7}$, while the detailed structure remains unclear. In this work, we explore the stability and physical properties of such an interesting system by using density functional theory and the $U$ parameter simulation method implemented in VASP. The results show that the enthalpy of La$_{2}$PrNi$_{2}$O$_{7}$ is slightly larger than its parent material bilayer R-P nickelate La$_{3}$Ni$_{2}$O$_{7}$. The electronic structure analysis indicates that near the Fermi level, the e$_{\rm g}$ orbit of Ni dominates and strongly hybridizes with the 2p orbit of O, thereby forming a significant van Hove singularity that is conducive to superconductivity. The Amam phase to the $I4/mmm$ phase occurs, accompanied by an increase in the bandwidth of Ni 3d$_{z^{2}}$ and an enhancement of the bonding-antibonding splitting (from about 0.5 eV to 1.5 eV), which leads to an increase in the density of states at the Fermi level. Our findings provide insights into the preparation and superconductivity of R-P bilayer nickelate.

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Stable structures and superconductivity of Ca-As-H system under high pressure Lanci Guo(郭兰慈), Qiyue Zhang(张启悦), Yuechen Guo(郭悦晨), Gang Chen(陈刚), and Jurong Zhang(张车荣) Chin. Phys. B, 2025, 34 (11):  117401.  DOI: 10.1088/1674-1056/ae00ac Abstract ( 23 )   HTML ( 0 )   PDF (1709KB) ( 1 )   Obtaining room-temperature superconductors has long been a research hotspot in the field of condensed matter physics. Previous studies have shown that doping strategies can effectively enhance the superconducting properties of materials. In this work, we employed first-principles calculations combined with the particle swarm optimization method to explore the structural possibilities of the Ca-doped As-H ternary system and to calculate the electronic and superconducting properties of the newly identified structures. Two thermodynamically stable hydrides were found under high pressure. The $P$4/nmm-Ca$_{2}$AsH$_{4}$ phase remains thermodynamically stable within the pressure range of 90-200 GPa, while the Cc-Ca$_{2}$AsH$_{6}$ phase exhibits stability over a broader range of 79-200 GPa. Electron-phonon coupling analysis indicates that the superconducting critical temperatures ($T_{\rm c}$) of $P$4/nmm-Ca$_{2}$AsH$_{4}$ and Cc-Ca$_{2}$AsH$_{6}$ are 11 K and 16 K at 100 GPa, respectively. The incorporation of Ca significantly reduces the thermodynamic stability pressure of As-H compounds with higher hydrogen content, thereby improving their synthetic accessibility.

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Effect of metal solvent and growth surface on boron doping efficiency and impurity incorporation in HPHT-grown diamond single crystals Hongbo Li(李鸿波), Wenhao Wang(王文豪), Yadong Li(李亚东), Liangchao Chen(陈良超), Zhuangfei Zhang(张壮飞), Yuewen Zhang(张跃文), Qianqian Wang(王倩倩), Biao Wan(万彪), Chunlei Du(杜春雷), and Chao Fang(房超) Chin. Phys. B, 2025, 34 (11):  118101.  DOI: 10.1088/1674-1056/adfb55 Abstract ( 26 )   HTML ( 0 )   PDF (1988KB) ( 12 )   To enhance boron doping efficiency and reduce metal impurities in diamonds, selecting an appropriate metal solvent is essential for producing p-type diamonds using the high-pressure high-temperature (HPHT) method. This paper presents a detailed study of the properties and characteristics of boron-doped diamond (BDD) single crystals grown using FeNi and FeCo solvents through the HPHT method. The results indicate that, with the same TiB$_{2}$ addition ratio, BDD crystals grown using FeCo solvent have a higher concentration of uncompensated boron ions, resulting in improved boron doping efficiency. Additionally, by growing BDD in the same synthesis environment (FeCo-3 wt% TiB$_{2})$ using (111) and (100) seed crystals as growth surfaces, it was found that the boron content in the crystal grown from the (100) seed crystal was higher than that in the crystal grown from the (111) seed crystal. Additionally, the crystals grown with the FeCo solvent contained fewer metal elements (Fe and Co) compared to those produced with the FeNi solvent (Fe and Ni), which supported the growth of high-quality BDD single crystals. This indicated that the choice of growth planes significantly influences the incorporation of boron in diamonds. Our findings hold significant research value for the development of high-quality p-type diamond semiconductors using the HPHT method.

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Comparative study on electronic structures of two phases compounds and origin of the structural phase transition in LiFePO4 Peiru Yang(杨佩如), Xinchun Du(杜新春), Jie Li(李杰), and Siqi Shi(施思齐) Chin. Phys. B, 2025, 34 (11):  118201.  DOI: 10.1088/1674-1056/ae0bfe Abstract ( 22 )   HTML ( 0 )   PDF (1117KB) ( 4 )   LiFePO$_{4}$ has normal olivine-structured ($\alpha $-LFP) and high pressure ($\beta $-LFP) phases, with the former being one of the cathode materials for commercial Li-ion batteries. Despite extensive focus on the respective electrochemical properties of the two phases, there is a lack of comparative studies on their electronic and magnetic properties, and the origin of the structural phase transition remains unclear. By combining first-principles calculations with molecular dynamics simulations, we find that the anisotropic compression of Li-O bonds drives the structural phase transition from $\alpha $-LFP to $\beta $-LFP at a critical pressure of 20 GPa, while $\beta $-LFP undergoes a transition from semiconductor to metal due to Fe$^{3+}$ generated during delithiation. Their antiferromagnetic (AFM) ground states are predicted to arise from the negative magnetic exchange interactions between nearest and next-nearest neighbor sites, with the corresponding Néel temperature showing significant enhancement under pressure. Furthermore, compared with $\alpha $-LFP, $\beta $-LFP shows increases in bulk, shear, and Young's moduli of 8%, 13%, and 12%, respectively. These findings enrich the physical property data of LiFePO$_{4}$ phase compounds, providing knowledge for expanding the application scenarios of the $\alpha $-LFP phase under special operating conditions such as high pressure.

INSTRUMENTATION AND MEASUREMENT

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Development of a large-area 3He tube array neutron detector with frequency reduction capability Yan-Feng Wang(王艳凤), Li-Xin Zeng(曾莉欣), Liang Xiao(肖亮), Sheng Guo(郭胜), Jing-Jing Ma(马静静), Zhen-Hong Tan(谭振宏), Wu Xie(谢武), Wen-Hai Ji(季文海), Ping Miao(缪平), Hai-Yun Teng(滕海云), Pei-Xun Shen(沈培迅), Qing-Lei Xiu(修青磊), Xing-Fen Jiang(蒋兴奋), Hong Xu(许虹), Xiao-Juan Zhou(周晓娟), Meng-Qi Jiang(蒋孟奇), Lin Zhu(朱林), Lei Hu(胡磊), Jia-Jie Li(李嘉杰), Yong-Xiang Qiu(邱勇翔), Jian Zhuang(庄建), Yu-Bin Zhao(赵豫斌), Yuan-Bo Chen(陈元柏), Jian-Rong Zhou(周健荣), and Zhi-Jia Sun(孙志嘉) Chin. Phys. B, 2025, 34 (11):  116102.  DOI: 10.1088/1674-1056/adfefd Abstract ( 34 )   HTML ( 0 )   PDF (1676KB) ( 7 )   The time-of-flight high-resolution neutron diffractometer (TREND) at the China Spallation Neutron Source (CSNS) has been successfully equipped with a large-area $^{3}$He tube array neutron detector, designed to achieve exceptional resolution and uniformity. The detector system, comprising 14 banks and 134 modules with 1376 $^{3}$He tubes, is optimized for high-angle and medium-to-low-angle measurements. Advanced dual-end readout electronics ensure precise charge and time-of-flight measurements, while rigorous performance testing confirmed the system's spatial resolution and uniformity. In-situ testing using polyethylene samples validated the detector's operational stability, with counting rate deviations within 3.7%. The system also demonstrated excellent two-dimensional imaging capabilities and adaptability to various neutron wavelength ranges through harmonic division techniques. These results highlight the TREND detector system as a robust and versatile tool for high-resolution neutron diffraction studies.

COMPUTATIONAL PROGRAMS FOR PHYSICS

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Improved physics-informed neural networks incorporating lattice Boltzmann method optimized by tanh robust weight initialization Chenghui Yang(杨程晖), Minglei Shan(单鸣雷), Mengyu Feng(冯梦宇), Ling Kuai(蒯玲), Yu Yang(杨雨), Cheng Yin(殷澄), and Qingbang Han(韩庆邦) Chin. Phys. B, 2025, 34 (11):  110701.  DOI: 10.1088/1674-1056/adfc43 Abstract ( 29 )   HTML ( 0 )   PDF (2549KB) ( 9 )   Physics-informed neural networks (PINNs) have shown considerable promise for performing numerical simulations in fluid mechanics. They provide mesh-free, end-to-end approaches by embedding physical laws into their loss functions. However, when addressing complex flow problems, PINNs still face some challenges such as activation saturation and vanishing gradients in deep network training, leading to slow convergence and insufficient prediction accuracy. We present physics-informed neural networks incorporating lattice Boltzmann method optimized by tanh robust weight initialization (T-PINN-LBM) to address these challenges. This approach fuses the mesoscopic lattice Boltzmann model with the automatic differentiation framework of PINNs. It also implements a tanh robust weight initialization method derived from fixed point analysis. This model effectively mitigates activation and gradient decay in deep networks, improving convergence speed and data efficiency in multiscale flow simulations. We validate the effectiveness of the model on the classical arithmetic example of lid-driven cavity flow. Compared to the traditional Xavier initialized PINN and PINN-LBM, T-PINN-LBM reduces the mean absolute error (MAE) by one order of magnitude at the same network depth and maintains stable convergence in deeper networks. The results demonstrate that this model can accurately capture complex flow structures without prior data, providing a new feasible pathway for data-free driven fluid simulation.

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VASPilot: MCP-facilitated multi-agent intelligence for autonomous VASP simulations Jiaxuan Liu(刘家轩), Tiannian Zhu(朱天念), Caiyuan Ye(叶财渊), Zhong Fang(方忠), Hongming Weng(翁红明), and Quansheng Wu(吴泉生) Chin. Phys. B, 2025, 34 (11):  117106.  DOI: 10.1088/1674-1056/ae0681 Abstract ( 30 )   HTML ( 0 )   PDF (1799KB) ( 5 )   Density-functional-theory (DFT) simulations with the Vienna Ab initio Simulation Package (VASP) are indispensable in computational materials science but often require extensive manual setup, monitoring, and postprocessing. Here, we introduce VASPilot, an open-source platform that fully automates VASP workflows via a multi-agent architecture built on the CrewAI framework and a standardized model context protocol (MCP). VASPilot's agent suite handles every stage of a VASP study from retrieving crystal structures and generating input files to submitting Slurm jobs, parsing error messages, and dynamically adjusting parameters for seamless restarts. A lightweight Quart-based web interface provides intuitive task submission, real-time progress tracking, and drill-down access to execution logs, structure visualizations, and plots. We validated VASPilot on both routine and advanced benchmarks: automated band-structure and density-of-states calculations (including on-the-fly symmetry corrections), plane-wave cutoff convergence tests, lattice-constant optimizations with various van der Waals corrections, and cross-material band-gap comparisons for transition-metal dichalcogenides. In all cases, VASPilot completed the missions reliably and without manual intervention. Moreover, its modular design allows easy extension to other DFT codes simply by deploying the appropriate MCP server. By offloading technical overhead, VASPilot enables researchers to focus on scientific discovery and accelerates high-throughput computational materials research.

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Accurate quantum critical points and nonlocal string order parameters in the spin tetrahedron chain Zhi-Yong Wu(吴志勇), Kai-Ming Zhang(张凯铭), and Li-Xiang Cen(岑理相) Chin. Phys. B, 2025, 34 (11):  117502.  DOI: 10.1088/1674-1056/ae0c7c Abstract ( 41 )   HTML ( 0 )   PDF (749KB) ( 16 )   The ground-state phase diagram and nonlocal order parameters of an infinite spin tetrahedron chain with inhomogeneous exchange couplings are investigated. It is shown that the phase boundaries of the three phases in the model can be determined precisely, in line with the precision of its ground-state energy. Numerical calculations using the regularized time-evolving block decimation (rTEBD) algorithm yield the locations of the two quantum critical points with an accuracy about $10$ digits. Moreover, we explain how to calculate the parity-associated string order for the output wave function obtained through the rTEBD procedure, which not only reveals the presence of long-range correlations but also identifies the symmetry-protected topological order within the intermediate phase of the model.

RAPID COMMUNICATION

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Information scrambling in a partially confined quantum link model Yifan Luo(罗祎帆), Zheng Tang(唐正), Li Chen(陈立), and Wei Zheng(郑炜) Chin. Phys. B, 2025, 34 (11):  110301.  DOI: 10.1088/1674-1056/ae00b1 Abstract ( 32 )   HTML ( 0 )   PDF (2376KB) ( 4 )   Quantum link models (QLMs) serve as experimentally accessible platforms for studying lattice gauge theories with finite-dimensional Hilbert spaces. In this work, we investigate information scrambling in the partially confined phase of a spin-1 quantum link model by calculating the dynamics of out-of-time-ordered correlators (OTOCs) and entanglement entropy. We observe that, in the partially confined phase, information scrambling exhibits significant asymmetry, manifested as the unidirectional propagation of both OTOCs and entanglement entropy. This phenomenon stands in stark contrast to the isotropic spreading observed in the deconfined phase and the localization characteristic of the confined phase. Furthermore, the simultaneous occurrence of the unidirectional propagation of both OTOCs and entanglement entropy, together with the $\theta$-induced asymmetric excitation propagation, reveals a direct connection between information scrambling and charge confinement.

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Efficient characterization of the coupler spectrum via sideband driving in superconducting qubits Hot! Jianwen Xu(徐建文), Ruonan Guo(郭若男), Wen Zheng(郑文), Yu Zhang(张钰), Jie Zhao(赵杰), Zhiguo Huang(黄智国), Jingwei Wen(闻经纬), Runqing Zhang(张润清), Shaoxiong Li(李邵雄), Xinsheng Tan(谭新生), and Yang Yu(于扬) Chin. Phys. B, 2025, 34 (11):  110302.  DOI: 10.1088/1674-1056/ae00b0 Abstract ( 52 )   HTML ( 0 )   PDF (1198KB) ( 42 )   Fabrication-friendly superconducting qubits continue to be a leading candidate for scalable quantum computing. Recent developments in tunable couplers have significantly advanced the progress toward practical quantum processors. However, high-performance quantum control, particularly two-qubit gates, depends on the delicate tuning of the coupler spectrum, as misalignment can lead to undesirable phenomena such as frequency crowding, which may cause errors including state leakage. Here, we propose an efficient method for characterizing the coupler spectrum through sideband drivings, obviating the need for additional components in current quantum processors. We demonstrate this technique experimentally by employing both continuous-wave and pulsed measurement protocols, successfully extracting the coupler spectrum. Furthermore, by utilizing the measured coupler spectrum, we calibrate the frequency dependence of the effective coupling strength between two qubits linked by the coupler. The proposed approach offers significant practical benefits, enabling the efficient characterization of the coupler spectrum in existing quantum architectures, thus paving the way for enhanced quantum control and scalability.

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Precision calculation of 4,6,8He isotope shifts Hot! Xiao-Qiu Qi(戚晓秋), Xing-Han Dong(董星汉), Fang-Fei Wu(吴芳菲), Zong-Chao Yan(严宗朝), Li-Yan Tang(唐丽艳), Zhen-Xiang Zhong(钟振祥), and Ting-Yun Shi(史庭云) Chin. Phys. B, 2025, 34 (11):  113101.  DOI: 10.1088/1674-1056/adf82c Abstract ( 38 )   HTML ( 3 )   PDF (562KB) ( 15 )   Standard perturbation theory is employed to calculate the mass shifts of the $2\,^1\!{\rm S}_0$-$2\,^3\!{\rm S}_1$ and $2\,^3\!{\rm S}_1$-$2\,^3\!{\rm P}_{\rm J}$ transitions for $^{4,6,8}{\rm He}$. High-precision results are obtained for the mass shifts in the isotope pairs $^6{\rm He}$-$^4{\rm He}$ and $^8{\rm He}$-$^4{\rm He}$, with uncertainties below 1 part per million (ppm). Our analysis provides a complete set of isotope-shift results and systematically examines their sensitivity to nuclear charge-radius differences. Once experimental measurements reach a precision comparable to that of the calculated mass shifts, the squared differences of nuclear charge radii can be determined with an accuracy of approximately $0.4\%$-$0.6\%$, representing an order-of-magnitude improvement over current values.

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Stabilizing 459 nm passive optical clock for pumping 1470 nm active optical clock Haoyang Wu(吴浩洋), Zhiqiang Wen(温智强), Chen Wang(王琛), Zhenfeng Liu(刘珍峰), Jingbiao Chen(陈景标), Shougang Zhang(张首刚), and Deshui Yu(于得水) Chin. Phys. B, 2025, 34 (11):  114201.  DOI: 10.1088/1674-1056/adfefa Abstract ( 85 )   HTML ( 0 )   PDF (1455KB) ( 64 )   Optical clocks with thermal atoms are characterized by compact size, simple structure, reduced weight, and low power consumption and have the potential for broad out-of-the-lab and commercial applications. Here, we demonstrate a 459 nm optical clock based on the 6S$_{1/2}$-7P$_{1/2}$ transition in thermal $^{133}$Cs atoms. Two methods, modulation transfer spectroscopy (MTS) and frequency modulation spectroscopy (FMS), are employed to stabilize the frequency of a 459 nm commercial laser to the atomic transition. The MTS-MTS and MTS-FMS beat-note measurements show short-term frequency stabilities of $3.7\times10^{-13}/\sqrt{\tau}$ and $6.4\times10^{-13}/\sqrt{\tau}$, respectively, at the averaging time $\tau$. The 459 nm passive optical clock further serves as the pump for an active 1470 nm optical clock based on the cavityless lasing. The resultant 1470 nm output power reaches over 10 μW and the pump-beam-induced light shift is estimated to be $2\pi\times11$ Hz with a fractional uncertainty of $2.4\times10^{-18}$. These results demonstrate the feasibility of hybridizing passive and active optical clocks, providing a promising route toward compact multi-wavelength optical frequency standards.

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A dynamic crossover with possibly universal dynamic signatures in simple glass-forming liquids Hot! Yiming Zheng(郑一鸣), Mingyu Zhu(朱明宇), Licun Fu(付立存), Pengfei Guan(管鹏飞), and Lijin Wang(王利近) Chin. Phys. B, 2025, 34 (11):  116103.  DOI: 10.1088/1674-1056/adfdb5 Abstract ( 46 )   HTML ( 0 )   PDF (714KB) ( 12 )   On approaching the glass transition, the structural relaxation of glass-forming liquids slows down drastically, along with a significant growth of dynamic heterogeneity. Recent studies have achieved substantial advancements in elucidating the quantitative correlations between structural relaxation and dynamic heterogeneity. Here, we present the discovery of a novel dynamic crossover with possibly universal dynamic signatures by investigating the relationship between structural relaxation and dynamic heterogeneity. Specifically, the structural relaxation time at the dynamic crossover $\tau_{\rm c}$ is equal to the time scale for the maximum non-Gaussian parameter, which could serve as a quantitative characterization of dynamic heterogeneity. The degree of dynamic heterogeneity at the crossover is approximately equivalent across all investigated glass-forming liquids, leading to a scaling collapse between structural relaxation and dynamic heterogeneity. Moreover, the mean squared displacement at the structural relaxation time is nearly constant across different temperatures as long as the structural relaxation time does not exceed $\tau_{\rm c}$. We further observe that the temperature at the dynamic crossover is lower than the onset temperature of slow dynamics. Our findings thus suggest the existence of a novel dynamic crossover with possibly universal dynamic signatures in glass-forming liquids, which merits in-depth investigations.

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Possible orthorhombic phase of Ta2O5 under high pressures Hot! Yan Gong(龚艳), Hui-Min Tang(唐慧敏), Yong Yang(杨勇), and Yoshiyuki Kawazoe Chin. Phys. B, 2025, 34 (11):  116104.  DOI: 10.1088/1674-1056/ae0925 Abstract ( 34 )   HTML ( 0 )   PDF (921KB) ( 13 )   A potential orthorhombic phase of Ta$_{2}$O$_{5}$, designated as Y-Ta$_{2}$O$_{5}$, is predicted under high-pressure conditions using density functional theory (DFT) combined with structural search algorithms. This phase, containing four formula units per unit cell ($Z= 4$), exhibits the highest Ta-O coordination numbers reported to date. Y-Ta$_{2}$O$_{5}$ is identified as the most energetically stable form of Ta$_{2}$O$_{5}$ within the pressure range of approximately 70 GPa to at least 200 GPa. Both standard DFT-GGA and higher-accuracy GW calculations indicate that Y-Ta$_{2}$O$_{5}$ is a wide-bandgap semiconductor with a direct bandgap. Furthermore, nuclear quantum effects (NQEs) introduce nontrivial corrections to external pressure at fixed volumes, underscoring their significance in high-pressure phase stability analyses.

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Dynamical structure factor and a new method to measure the pairing gap in two-dimensional attractive Fermi-Hubbard model Huaisong Zhao(赵怀松), Feng Yuan(袁峰), Tianxing Ma(马天星), and Peng Zou(邹鹏) Chin. Phys. B, 2025, 34 (11):  117102.  DOI: 10.1088/1674-1056/adfbd9 Abstract ( 33 )   HTML ( 0 )   PDF (1560KB) ( 10 )   The measurement of the pairing gap is crucial for investigating the physical properties of superconductors or superfluids. We propose a strategy to measure the pairing gap through the dynamical excitations. With the random phase approximation (RPA), we study the dynamical excitations of a two-dimensional attractive Fermi-Hubbard model by calculating its dynamical structure factor. Two distinct collective modes emerge: a Goldstone phonon mode at transferred momentum ${\bm q}=\left[0,0\right]$ and a roton mode at ${\bm q}=\left[\pi,\pi\right]$. The roton mode exhibits a sharp molecular peak in the low-energy regime. Notably, the area under the roton molecular peak scales with the square of the pairing gap, which holds even in three-dimensional and spin-orbit coupled (SOC) optical lattices. This finding suggests an experimental approach to measure the pairing gap in lattice systems by analyzing the dynamical structure factor at ${\bm q}=\left[\pi,\pi\right]$.

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Thickness dependence of linearly polarized light-induced momentum anisotropy and inverse spin Hall effect in topological insulator Bi2Te3 Jiayi Qiu(邱嘉毅), Jinling Yu(俞金玲), Zhu Diao(刁佇), Yunfeng Lai(赖云锋), Shuying Cheng(程树英), Yonghai Chen(陈涌海), and Ke He(何珂) Chin. Phys. B, 2025, 34 (11):  117103.  DOI: 10.1088/1674-1056/adf82a Abstract ( 20 )   HTML ( 0 )   PDF (1300KB) ( 2 )   The thickness dependence of linearly polarized light-induced momentum anisotropy and the inverse spin Hall effect (PISHE) in topological insulator (TI) Bi$_{2}$Te$_{3}$ films has been investigated. A significant enhancement of the PISHE signal is observed in the 12-quintuple-layer (QL) Bi$_{2}$Te$_{3}$ film compared with that of the 3- and 5-QL samples, whereas a minimal value of photoinduced momentum anisotropy is found in the 12-QL sample. The photoinduced momentum anisotropy and the PISHE in Bi$_{2}$Te$_{3}$ films are more than three and two orders of magnitude larger than those in Bi$_{2}$Se$_{3}$ films grown on SrTiO$_{3}$ substrates, respectively. The 3-QL sample exhibits a sinusoidal dependence of the PISHE current on the light spot position, while the 5-QL and 12-QL samples show a W-shaped dependence, which arises from the different angles between the coordinate axis $x$ and the in-plane crystallographic axis of the Bi$_{2}$Te$_{3}$ films. Our findings demonstrate the critical role of film thickness in modulating both the photoinduced momentum anisotropy and the PISHE current, thereby suggesting a thickness-engineering strategy for designing novel optoelectronic devices based on TIs.

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Unconventional superconductivity in Cr-based nitride La3Cr10-xN11 Hot! M Y Zou(邹牧远), J C Jiao(焦嘉琛), K W Chen(陈锴文), C Y Jiang(姜程予), C S Chen(陈长胜), X Li(李鑫), Q Wu(吴琼), N Y Zhang(张宁远), O O Bernal, P C Ho, A Koda, D E MacLaughlin, and L Shu(殳蕾) Chin. Phys. B, 2025, 34 (11):  117104.  DOI: 10.1088/1674-1056/ae001a Abstract ( 34 )   HTML ( 0 )   PDF (1290KB) ( 27 )   Magnetization, specific heat, and muon spin relaxation (μSR) experiments have been carried out on the Cr-based nitride superconductor La$_3$Cr$_{10-x}$N$_{11}$, which exhibits a number of unconventional superconducting properties. The susceptibility $\chi(T)$ shows nearly perfect superconducting diamagnetism ($4\pi\chi(T=0) \approx -1$) and a remarkably high upper critical field $\mu_0H_{\rm c2} = 11.2$ T. The specific heat displays activated exponential behavior $\exp(-\varDelta_0/k_{\rm B}T)$, together with a large and field-dependent residual Sommerfeld coefficient. Transverse-field muon spin relaxation (μSR) measurements suggest s+s-wave or p-wave pairing symmetry, ruling out single s-wave pairing. Zero-field μSR yields no statistically significant evidence for time reversal symmetry breaking (TRSB), and places an upper bound of 1.5(1.3) ms$^{-1}$ on any TRSB-induced muon relaxation rate at $T = 0$. Our results suggest that the unconventional superconductivity in $Ln_3\rm Cr_{10-x}N_{11}$, $Ln ={\rm La}$ and Pr, is mainly due to Cr 3d electrons and is similar in both compounds, whereas Pr 4f electrons are primarily responsible for the TRSB superconductivity observed in Pr$_3$Cr$_{10-x}$N$_{11}$.

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Asymmetric gaps of tetralayer graphene unveiled by thermodynamic characterization Zhuangzhuang Qu(曲壮壮), Zhuoxian Li(李卓贤), Boxi Li(李博熙), Lipeng Hou(侯立芃), Xiangyan Han(韩香岩), Qianling Liu(刘倩伶), Zhiyu Wang(王知雨), Kenji Watanabe, Takashi Taniguchi, Yanmeng Shi(史衍猛), and Jianming Lu(路建明) Chin. Phys. B, 2025, 34 (11):  117201.  DOI: 10.1088/1674-1056/adf9fc Abstract ( 25 )   HTML ( 0 )   PDF (14769KB) ( 8 )   Tetralayer graphene has shown several interesting properties such as tunable Lifshitz transitions, helical edge states, and high-temperature anomalous Hall effects. The band structure, which directly relates to these phenomena, has so far been predominantly determined by fitting Landau-level spectra. Here, by characterizing the electronic capacitance, we reveal unprecedented details of its band structure: the energy shift between the heavy- and light-mass band edges in the conduction band is much larger than that in the valence band. Their responses to displacement fields are also distinct: while the former increases monotonically and significantly, the latter first decreases and then increases slightly. Our results suggest that the interlayer interactions and hopping parameters are more complex than previously expected, calling for precise measurements of band structures in various multilayer van der Waals systems.

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Impact of p-GaN thickness on the transport properties of two-dimensional hole gases in a GaN/AlGaN/GaN heterostructure Pengfei Shao(邵鹏飞), Yifan Cheng (成毅凡), Yu Liu(柳裕), Qi Yao(姚齐), Zanjiang Qiao(乔赞江), Yanghu Peng (彭扬虎), Qin Cai(蔡青), Tao Tao(陶涛), Zili Xie(谢自力), Dunjun Chen(陈敦军), Bin Liu(刘斌), Rong Zhang(张荣), and Ke Wang(王科) Chin. Phys. B, 2025, 34 (11):  117301.  DOI: 10.1088/1674-1056/ae0397 Abstract ( 30 )   HTML ( 0 )   PDF (1208KB) ( 7 )   Polarization-induced two-dimensional hole gases (2DHG) in GaN/AlGaN/GaN heterostructures offer a promising pathway for advancing p-channel transistors. This work investigates the impact of p-GaN thickness on hole distribution and transport through temperature-dependent Hall measurements and TCAD simulations. It is demonstrated that the p-channel is composed of holes both in the p-GaN layer and in the 2DHG at the GaN/AlGaN heterointerface at 300 K, whereas at 77 K, the p-channel conduction is dominated solely by the 2DHG at the GaN/AlGaN heterointerface. The results also reveal the formation of a polarization-induced 2DHG at the GaN/AlGaN interface, exhibiting a high sheet density of $2.2\times 10^{13}$ cm$^{-2}$ and a mobility of 16.2 cm$^{2}\cdot$V$^{-1}\cdot$s$^{-1}$ at 300 K. The 2DHG sheet density remains nearly independent of p-GaN thickness when the p-GaN layer exceeds 30 nm. However, for p-GaN layers thinner than 30 nm, the 2DHG sheet density strongly depends on the p-GaN thickness, which is attributed to the gradual extension of the depletion region toward the GaN/AlGaN interface under the influence of surface trap states.

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Electron doping in FeSe monolayer and multilayer via metal phthalocyanine adsorption: A first-principles investigation Fangyu Yang(杨方玉), Yan-Fang Zhang(张艳芳), Peixuan Li(李佩璇), and Shixuan Du(杜世萱) Chin. Phys. B, 2025, 34 (11):  117302.  DOI: 10.1088/1674-1056/ae0396 Abstract ( 33 )   HTML ( 0 )   PDF (1471KB) ( 6 )   Electron doping has been established as an effective method to enhance the superconducting transition temperature and superconducting energy gap of FeSe thin films on strontium titanate (SrTiO$_3$) substrates. Previous studies have demonstrated that electron/hole doping can be achieved through the adsorption of metal phthalocyanine ($M$Pc, $M={\rm Co}$, Cu, Mn, Fe, and Ni) molecules on surfaces. This work explores the electron doping induced by the adsorption of MPc molecules, specifically cobalt phthalocyanine (CoPc) and copper phthalocyanine (CuPc), onto FeSe monolayer and multilayers. Utilizing first-principles calculations based on density functional theory, we demonstrate that charge rearrangement occurs when MPc molecules adsorb on the FeSe substrate, contributing to an accumulation of electrons at the interface. In the CoPc/FeSe systems, the electron accumulation increases with the layer number of FeSe substrate, converging for substrates with 3-5 layers. The analysis of the integrated planar charge difference up to the position with zero integrated charge transfer reveals that all the five MPc molecules donate electrons to the uppermost FeSe layer. The electron donation suggests that MPc adsorption can be a promising strategy to modulate the superconductivity of FeSe layers.

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Emergent ferroelectricity in the two-dimensional Janus MoSSe monolayer driven by nondegenerate phonon instability Zhi-Long Cao(曹智龙), Chen Cao(曹琛), Jia-Jun Xu(徐佳俊), Jia-Xu Yan(闫家旭), Lei Liu(刘雷), and De-Zhen Shen(申德振) Chin. Phys. B, 2025, 34 (11):  117305.  DOI: 10.1088/1674-1056/ae0d57 Abstract ( 30 )   HTML ( 0 )   PDF (3021KB) ( 8 )   We report the discovery of bistable polar states with switchable polarization in the Janus monolayer 1T-MoSSe, induced by symmetry breaking in its chalcogen atomic layers. Our results demonstrate that Janus 1T-MoSSe exhibits two out-of-plane bistable polar states with switchable polarization, rather than polarization emerging from a non-polar phase, which represents an unconventional form of ferroelectric-like behavior. First-principles calculations and phenomenological modeling reveal that the inequivalent stacking of sulfur and selenium (S/Se) atoms breaks central inversion symmetry, activating non-degenerate phonon modes at the $K$-point ($K_2/K_3$) that drive the structural transformation between metastable d1T$_{\rm S}$ and d1T$_{\rm Se}$ phases. This coupling enables bipolar control of out-of-plane polarization through atomic displacements and charge redistribution, resulting in a polarization change of $\Delta P \approx \pm 0.3 μ{\rm C/cm}^2$. The Landau free energy analysis indicates that anharmonic terms and inter-mode coupling generate an asymmetric double-well potential, which is essential for the stabilization of bistable polar states. Molecular dynamics simulations show that the d1T$_{\rm S}$ phase remains stable at high temperatures, whereas the d1T$_{\rm Se}$ phase undergoes an irreversible phase transition near 300 K, accompanied by a Peierls-like distortion of the Mo atomic chain. This transition is driven by differences in electronegativity, atomic radius, and d-p orbital hybridization between S and Se. Our findings establish a theoretical framework for engineering nonlinear responses in two-dimensional (2D) ferroelectrics and suggest that low-energy polarization reversal at room temperature can be achieved through strain or electric-field control, offering promising opportunities for non-volatile memory and piezoelectric sensing applications.

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High-frequency complex permeability calculation for metallic soft magnetic particles with easy magnetization plane in non-magnetic medium Hot! Liangrui Tan(谭梁睿), Donglin He(何东霖), Zhibiao Xu(徐志彪), Guowu Wang(王国武), Shengyu Yang(杨晟宇), Shaoyong Leng(冷绍勇), Ruilong Li(李睿龙), and Tao Wang(王涛) Chin. Phys. B, 2025, 34 (11):  117501.  DOI: 10.1088/1674-1056/ae00ad Abstract ( 29 )   HTML ( 0 )   PDF (3144KB) ( 8 )   Soft magnetic composites made from metallic magnetic particles with an easy magnetization plane (referred to as easy-plane metallic soft magnetic composites (SMC)) are considered ideal materials for the next generation of power electronic devices. This advantage is attributed to their ability to maintain high permeability at elevated frequencies. Despite these advantages, a definitive mathematical model that connects the high-frequency magnetic properties (e.g., effective permeability) of easy-plane metallic SMCs to the intrinsic properties of the particles is still lacking. In this work, a theoretical calculation model for the effective permeability of easy-plane metallic SMCs was formulated. This model was derived from a skin effect-corrected Landau-Lifshitz-Gilbert (LLG) equation and integrated with effective medium theory incorporating inter-particle interaction. To validate the model, we prepared samples of easy-plane Y$_{2}$Co$_{17}$ particle/PU SMCs with varying particle sizes and volume fractions. The experimental results showed a strong agreement with the calculated values. This research offers critical theoretical backing for the design and optimization of soft magnetic materials intended for high-frequency applications.

GENERAL

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Impact of peer pressure on cooperation evolution in the networked prisoner’s dilemma game with migration mechanisms Xianjia Wang(王先甲), Yanan Li(李亚楠), and Zhipeng Yang(杨志鹏) Chin. Phys. B, 2025, 34 (11):  110201.  DOI: 10.1088/1674-1056/ade425 Abstract ( 42 )   HTML ( 0 )   PDF (1184KB) ( 30 )   In social and ecological systems, individual migration behavior and peer pressure are crucial factors influencing decision-making and cooperative behavior. However, how migration regulates the evolution of cooperation and the specific role of peer pressure in this process remain to be further investigated. To address this, this study develops a model that incorporates migration mechanisms and peer pressure within the framework of the networked prisoner's dilemma game. Specifically, we modify the population structure and introduce a migration strategy based on payoff maximization, enabling individuals to dynamically adjust their positions according to the local environment. The model also considers the impact of peer pressure on individual decision-making and introduces heterogeneity in individuals' sensitivity to pressure, thereby systematically examining the role of both factors in the evolution of cooperative behavior. Based on this framework, we further compare our model with a scenario in which no migration mechanism is present to evaluate its impact on cooperative dynamics. The results reveal that the migration mechanism significantly promotes the evolution of cooperative behavior. Under this mechanism, higher individual sensitivity leads to an increased level of cooperation, and stronger peer pressure intensity more effectively enhances the promotion of cooperation. Additionally, the influence of population structure on cooperation frequency cannot be overlooked. An increase in vacant nodes provides cooperators with greater buffering space and more migration opportunities, making cooperative behavior more stable and facilitating its propagation within the system. These findings suggest that appropriately regulating individual mobility and reinforcing peer pressure constraints can enhance the stability and propagation of cooperative behavior, providing significant theoretical support for social governance, organizational management, and group collaboration.

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Exceptional rings and non-Abelian topology in non-Hermitian high-spin systems Peng-Zhen Sun(孙鹏震), Zhou-Tao Lei(雷周涛), and Yuan-Gang Deng(邓元刚) Chin. Phys. B, 2025, 34 (11):  110303.  DOI: 10.1088/1674-1056/addcbe Abstract ( 25 )   HTML ( 0 )   PDF (4760KB) ( 6 )   Topological phases featuring non-Abelian charges have garnered significant attention in recent years. In parallel, the study of multiband exceptional topology in non-Hermitian systems has emerged as a prominent research direction. In this study, we investigate a parity-time (PT) symmetric Hamiltonian, which hosts both conventional non-Abelian topological phases (NATPs) and hybrid phases. We propose an experimental scheme using spin-1 atoms with spin-orbit coupling trapped in two-dimensional (2D) lattices. Before adding a non-Hermitian term, we find the emergence of distinct topological phases mixed by two NATPs and establish their connection with NATPs theory. When a non-Hermitian term that preserves $PT$ symmetry protection was introduced, stable second-order exceptional rings and third-order exceptional points emerge and they drive the edge states to manifest as discontinuous Fermi arcs in the surface Brillouin zone. However, with the variation of the non-Hermitian term, it is rather intriguing that two types of exceptional rings here transition from being internally tangent to externally tangent, transforming into a new topological phase equivalent to the Hermitian case. This research provides deeper insights into the nature of NATPs and the topological implications of exceptional structures, contributing to the field of topological physics.

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Observation of topology of non-Hermitian systems without chiral symmetry Shuo Wang(王硕), Zhengjie Kang(康正杰), Hao Li(李浩), Jiaojiao Li(李姣姣), Yuanjie Zhang(张元杰), and Zhihuang Luo(罗智煌) Chin. Phys. B, 2025, 34 (11):  110304.  DOI: 10.1088/1674-1056/addcc1 Abstract ( 13 )   HTML ( 0 )   PDF (4921KB) ( 5 )   Topological invariants are crucial for characterizing topological systems. However, experimentally measuring them presents a significant challenge, especially in non-Hermitian systems where the biorthogonal eigenvectors are often necessary. We propose a general approach for measuring the topological invariants of one-dimensional non-Hermitian systems, which can be derived from the spin textures of right eigenstates. By utilizing a dilation method, we realize a non-Hermitian system without chiral symmetry on a two-qubit nuclear magnetic resonance system and measure the winding number associated with the eigenstates. In addition to examining the topology of the eigenstates, our experiment also reveals the topological structure of the energy band, which differs from that in chiral systems. Our work paves the way for further exploration of complex topological properties in non-Hermitian systems without chiral symmetry.

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PT-symmetry phase transition in a bipartite lattice with long-range interactions Dapeng Zheng(郑大鹏), Siwu Li(李思吾), and Zeliang Xiang(项泽亮) Chin. Phys. B, 2025, 34 (11):  110305.  DOI: 10.1088/1674-1056/addcd4 Abstract ( 32 )   HTML ( 0 )   PDF (3351KB) ( 2 )   We investigate the parity-time $(\mathcal{PT})$ symmetry-breaking quantum phase transition in a one-dimensional (1D) bosonic lattice featuring cavity-mediated long-range interactions and spatially staggered dissipation. By mapping the system to an effective spin chain under the constraints of hard-core bosons and integrating the mean-field decoupling approach with biorthogonal basis formalism, we derive a self-consistency equation. Numerical simulation results validate that the derived equation quantitatively captures the $\mathcal{PT}$-symmetry order parameter's phase diagram. Our findings reveal that coherent hopping maintains $\mathcal{PT}$ symmetry through quantum fluctuations. Conversely, cavity-engineered long-range interactions, in synergy with staggered dissipation, act in opposition to drive symmetry breaking. This competitive interplay can inspire further exploration of tunable quantum phase transitions in non-Hermitian systems.

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An SOT-switchable micromagnet scheme of adiabatic geometric gates for silicon spin qubits Fang-Ge Li(李方阁), Ranran Cai(蔡冉冉), Bao-Chuan Wang(王保传), Hai-Ou Li(李海欧), Gang Cao(曹刚), and Guo-Ping Guo(郭国平) Chin. Phys. B, 2025, 34 (11):  110306.  DOI: 10.1088/1674-1056/addcd3 Abstract ( 22 )   HTML ( 0 )   PDF (1081KB) ( 3 )   Geometric phase gates have attracted considerable attention due to their intrinsic robustness against certain types of noise. Significant progress has been achieved in implementing geometric phase gates using microwave control in silicon-based electron spin systems. In this work, we propose an alternative geometric phase gate protocol that differs fundamentally from microwave driving approaches by leveraging square-wave control of rapidly switchable micromagnets driven by spin-orbit torque (SOT) to achieve fast and precise magnetic field modulation. By employing square-wave currents to control magnetization switching, our approach relaxes the requirements on waveform precision while significantly suppressing crosstalk. Moreover, our scheme inherently preserves trajectory closure at the end of each operation, effectively mitigating noise-induced path deviation and enhancing gate robustness even under strong noise conditions, thereby offering a promising pathway toward efficient and reliable quantum operations in large-scale qubit arrays.

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Construction methods of nonlocal sets of orthogonal product states on multipartite quantum systems Guang-Bao Xu(徐光宝), Zhao-Xia Zhong(仲昭霞), Yu-Guang Yang(杨宇光), and Dong-Huan Jiang(姜东焕) Chin. Phys. B, 2025, 34 (11):  110307.  DOI: 10.1088/1674-1056/addcd5 Abstract ( 13 )   HTML ( 0 )   PDF (638KB) ( 2 )   Nonlocal set of orthogonal product states (OPSs) can improve the confidentiality of information when it is used to design quantum cryptographic protocols. It is a difficult question how to construct a nonlocal set of OPSs on general multipartite and high dimensional quantum systems. Different from the previous works, we first present a novel method for constructing a nonlocal product set with $3d-2$ members on $\mathbb{C}^{d}\otimes \mathbb{C}^{d} \otimes \mathbb{C}^{d}$ quantum system for $d\ge 3$. Then, we extend this construction method to $\mathbb C^{d_{1}} \otimes \mathbb C^{d_{2} } \otimes \mathbb C^{d_{3} }$ quantum system and ${\otimes_{i=1}^{n}} \mathbb C^{d_{i} } $ quantum system respectively, where $3\le d_{1} \le d_{2}\le d_{3}\le \dots \le d_{n}$ and $n \geq 3$. The nonlocal set of OPSs constructed by our method contains fewer elements than those constructed by the existing methods, except for one special case. More importantly, the set of states constructed by our method has a completely different structure from those constructed by the existing methods since our nonlocal set does not contain a ``stopper" state. Our result is helpful to further understand the different structures of nonlocal sets on multipartite systems.

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Measurement-device-independent quantum dialogue protocol with bidirectional identity authentication Shi-Pu Gu(顾世浦), Jia-Wei Ying(应佳伟), Xing-Fu Wang(王兴福), Lan Zhou(周澜), and Yu-Bo Sheng(盛宇波) Chin. Phys. B, 2025, 34 (11):  110308.  DOI: 10.1088/1674-1056/addd81 Abstract ( 9 )   HTML ( 0 )   PDF (2076KB) ( 4 )   Quantum dialogue (QD) realizes the real-time secure bidirectional quantum communication. Measurement-device-independent (MDI) QD can resist all possible attacks focusing on the imperfect measurement devices and enhance QD's practical security. However, in practical applications, any secure communication requires identity authentication as a prerequisite. In this paper, we propose an MDI QD protocol with bidirectional identity authentication. The practical communication parties can first authenticate the identity of each other simultaneously before the message exchange. In theory, our MDI QD protocol has unconditional security and the communication parties can exchange 1.5 bits of messages in each communication round with linear optical Bell state measurement. We numerically simulate the secrecy message capacity of our MDI QD protocol. Our protocol has two advantages. First, it can effectively resist the impersonation attack and enhance MDI QD's practical security. Second, it does not require keys to assist the message exchange and has relatively high efficiency. Our protocol has application potential in the future quantum communication field.

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Dynamical evolution of imaginarity resources in non-Markovian environments Hong-Biao Li(李宏彪), Deng-Guo Kong(孔德国), Xue-Ping Chai(柴学平), Jin-Long Yu(余金龙), and Qiang Zheng(郑强) Chin. Phys. B, 2025, 34 (11):  110309.  DOI: 10.1088/1674-1056/ade4b1 Abstract ( 42 )   HTML ( 0 )   PDF (1559KB) ( 12 )   The pivotal role of complex numbers in quantum mechanics underpins the resource theory of imaginarity. We investigate imaginarity dynamics in a single-qubit open system coupled to a non-Markovian environment. Crucially, cavity field detuning emerges as the dominant regulator, driving continuous conversion between the real and imaginary components of coherence. Nonzero detuning induces characteristic non-periodic oscillations of imaginarity between zero and maximal values, preventing complete decoherence at specific times. We establish that imaginarity resources stem from both intrinsic system evolution and environmental feedback. Significantly, detuning-driven imaginarity generation persists even in Markovian regimes, demonstrating its origin beyond environmental memory effects. These insights offer new perspectives for understanding and harnessing quantum coherence.

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Four-body interactions in the long-range Hamiltonian mean-field model Qiang Zhang(张强), Haojie Luo(罗浩杰), Bingling Cen(岑炳玲), and Yu Xue(薛郁) Chin. Phys. B, 2025, 34 (11):  110501.  DOI: 10.1088/1674-1056/addccf Abstract ( 29 )   HTML ( 0 )   PDF (629KB) ( 2 )   A Hamiltonian mean-field model with long-range four-body interactions is proposed. The model describes a long-range mean-field system in which $N$ unit-mass particles move on a unit circle. Each particle $\theta_{i}$ interacts with any three other particles through an infinite-range cosine potential with an attractive interaction ($\varepsilon > 0$). By applying a method that remaps the average phase of global particle pairs onto a new unit circle, and using the saddle-point technique, the partition function is solved analytically after introducing four-body interactions, yielding expressions for the free energy $f$ and the energy per particle $U$. These results were further validated through numerical simulations. The results show that the system undergoes a second-order phase transition at the critical energy $U_{\rm c}$. Specifically, the critical energy corresponds to $U_{\rm c}=0.32$ when the coupling constant $\varepsilon =5$, and $U_{\rm c}=0.63$ when $\varepsilon =10$. Finally, we calculated the system's largest Lyapunov exponent $\lambda $ and kinetic energy fluctuations $\varSigma $ through numerical simulations. It is found that the peak of the largest Lyapunov exponent $\lambda $ occurs slightly below the critical energy $U_{\rm c}$, which is consistent with the point of maximum kinetic energy fluctuations $\varSigma $. And there is a scaling law of $\varSigma /N^{1/2}\propto \lambda $ between them.

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Periodic lump, soliton, and some mixed solutions of the (2+1)-dimensional generalized coupled nonlinear Schrödinger equations Xiao-Min Wang(王晓敏), Ji Li(李吉), and Xiao-Xiao Hu(胡霄骁) Chin. Phys. B, 2025, 34 (11):  110502.  DOI: 10.1088/1674-1056/ae1019 Abstract ( 14 )   HTML ( 0 )   PDF (1592KB) ( 7 )   The (2+1)-dimensional generalized coupled nonlinear Schrödinger equations with a four-wave mixing term are studied in this paper, which describe optical solitons in birefringent fibers. Utilizing the Hirota bilinear method, we systematically construct single- and double-periodic lump solutions. To provide a detailed insight into the dynamic behavior of the nonlinear waves, we explore diverse mixed solutions, including bright-dark, W-shaped, multi-peak, and bright soliton solutions. Building upon single-periodic lump solutions, we analyze the dynamics of lump waves on both plane-wave and periodic backgrounds using the long-wave limit method. Moreover, we obtain the interaction solutions involving lumps, periodic lumps, and solitons. The interactions among two solitons, multiple lumps, and mixed waves are illustrated and analyzed. Comparative analysis reveals that these multi-lump solutions exhibit richer dynamical properties than conventional single-lump ones. These results contribute to a deeper understanding of nonlinear systems and may facilitate solving nonlinear problems in nature.

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Cu/PTFE triboelectric nanogenerator for Morse code and array information detection Yulin Yan(闫玉霖), Yiming Qi(齐一鸣), and Huaisheng Wang(王槐生) Chin. Phys. B, 2025, 34 (11):  110702.  DOI: 10.1088/1674-1056/ae039b Abstract ( 42 )   HTML ( 0 )   PDF (1364KB) ( 10 )   The application of triboelectric nanogenerators (TENGs) for collecting and converting waste energy into usable electrical energy has been widely reported. However, their practical application in real-time, self-powered communication systems, particularly for robust information transmission, remains underexplored. To achieve stable self-energy supply information transmission, this study presents a lightweight and flexible single-electrode TENG sensor based on a copper (Cu) foil and polytetrafluoroethylene (PTFE) composite. We systematically studied the stability of the device and found that it could maintain an output voltage of approximately 9 V after being stored at room temperature for 1 month. We also evaluated its power generation capacity, which was demonstrated by successfully lighting up to seven LEDs simultaneously. Additionally, we utilized its unique voltage signal to transmit Morse code and successfully sent the messages ``SOS" and ``HELLO" over a long distance. Furthermore, a $2\times 2$ TENG array was fabricated and tested, confirming excellent channel independence with minimal crosstalk during simultaneous or selective activation. This work demonstrates that the Cu/PTFE TENG sensor is not only a stable energy harvester but also a viable platform for self-powered communication and distributed sensing and holds promise in applications integrating flexible electronics and the Internet of things.

ATOMIC AND MOLECULAR PHYSICS

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A time-dependent generalized Floquet calculation of the laser-induced lineshape in attosecond transient absorption spectra Xu-Han Wang(王旭涵), Di Zhao(赵迪), and Peng-Bo Li(李蓬勃) Chin. Phys. B, 2025, 34 (11):  113201.  DOI: 10.1088/1674-1056/ae07c0 Abstract ( 25 )   HTML ( 0 )   PDF (1230KB) ( 5 )   We introduce a time-dependent generalized Floquet (TDGF) approach to calculate attosecond transient absorption spectra of helium atoms subjected to the combination of an attosecond extreme ultraviolet (XUV) pulse and a delayed few-cycle infrared (IR) laser pulse. This TDGF approach provides a Floquet understanding of the laser-induced change of resonant absorption lineshape. It is analytically demonstrated that the phase shift of the time-dependent dipole moment that results in the lineshape changes consists of two components, the adiabatic laser-induced phase (LIP) due to the IR-induced Stark shifts of adiabatic Floquet states and the non-adiabatic phase correction due to the non-adiabatic IR-induced coupling between adiabatic Floquet states. Comparisons of the spectral lineshape calculated based on the TDGF approach with the results obtained with the LIP model [Phys. Rev. A 88 033409 (2013)] and the rotating-wave approximation (RWA) are presented for several typical cases, demonstrating that TDGF universally and accurately captures IR-induced lineshape changes. It is suggested that the LIP model works as long as the generalized adiabatic theorem [PRX Quantum 2 030302 (2021)] holds, and the RWA works when the higher-order IR-coupling effect in the formation of adiabatic Floquet states is neglectable.

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Experiment study of energy redistribution during collisions of the excited state H2(1, 7) with LiH Kai Wang(王凯), Zhong Liu(刘中), Shuying Wang(王淑英), Chu Qin(秦楚), Zilei Yu(於子雷), and Xiaofang Zhao(赵小芳) Chin. Phys. B, 2025, 34 (11):  113401.  DOI: 10.1088/1674-1056/add502 Abstract ( 20 )   HTML ( 0 )   PDF (761KB) ( 1 )   The H$_{2}$ was excited to the H$_{2}$ X$^{1}\Sigma ^+_{\rm g}$ ($v=1$, $J=7$) energy level by the stimulated Raman pumping (SRP) technique, and the process of energy redistribution between H$_{2}(1,7)$ molecule and LiH was studied. The particle population density of H$_{2}(1,7)$ energy level is obtained by the coherent anti-Stokes Raman scattering (CARS) technique. The particle population density of each rotational level of H$_{2}$ ($v=1$, $J=7$, 5, 3) is analyzed with temperature after the collision between H$_{2}(1,7)$ molecule and LiH. It is found that the particle population density of each level increases with the increase in temperature after the collision. The time-resolved CARS spectra of each rotational energy level of H$_{2}$ ($v=1$, $J=7$, 5, 3) are analyzed at different temperatures. It is found that a multi-quantum relaxation process with $\Delta J=4$ occurs in H$_{2}(1,7)$ molecule, and the temperature accelerates the relaxation process. The effective lifetime of H$_{2}(1,7)$ energy level is obtained by plotting the semi-logarithmic plots of the CARS signal intensity and delay time of the level, and observing the law of the effective lifetime change with the temperature. It is found that the effective lifetime of H$_{2}(1,7)$ energy level shows an obvious decreasing trend with the increase of temperature.

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Experimental and theoretical study on electronic structure of toluene by electron momentum spectroscopy Guangqing Chen(陈广庆), Tuo Liu(刘拓), Yuting Zhang(张雨亭), Chenghong Zou(邹成宏), Maomao Gong(宫毛毛), Song-Bin Zhang(张松斌), Chunkai Xu(徐春凯), Enliang Wang(王恩亮), Xu Shan(单旭), and Xiangjun Chen(陈向军) Chin. Phys. B, 2025, 34 (11):  113402.  DOI: 10.1088/1674-1056/addce8 Abstract ( 23 )   HTML ( 0 )   PDF (1361KB) ( 4 )   The binding energy spectra and electron momentum distributions (EMDs) of valence orbitals in toluene molecule were measured by (e, 2e) electron momentum spectrometer. A comprehensive analysis of molecular vibrational effects on the EMDs was conducted through harmonic analytical quantum mechanical approach calculations and molecular dynamics simulations within the plane wave impulse approximation (PWIA). Furthermore, the multicenter three-distorted-wave method was employed to investigate the validity of the PWIA. A comparison between experimental measurements and theoretical predictions demonstrates that molecular vibrations have negligible effects on the EMDs, whereas the distorted-wave effects are obvious, particularly in large momentum regions.

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

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Nonreciprocal unidirectional and circular transmission in microcavity exciton polaritons Hong-Ping Xu(徐红萍), Run-Run Yang(杨润润), Ji-Ming Gao(高吉明), and Zi-Fa Yu(鱼自发) Chin. Phys. B, 2025, 34 (11):  114202.  DOI: 10.1088/1674-1056/adee8c Abstract ( 32 )   HTML ( 0 )   PDF (933KB) ( 5 )   We investigate nonreciprocal transmission in microcavity exciton polaritons and obtain analytical conditions for achieving unidirectional and circular transmission. The phase difference between two effective optomechanical couplings can regulate the interference of different channels between two photon modes, and control the direction of nonreciprocity, resulting in unidirectional forward and backward transmissions. Perfect nonreciprocal unidirectional transmission with zero losses is realized, which depends on exciton-photon-phonon couplings. Moreover, clockwise and counterclockwise circular transmissions are implemented by appropriately adjusting the phase of photon mode couplings. Our results open up exciting possibilities for implementing nonreciprocal photonic devices.

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Engineering an anisotropic Dicke model of Rydberg atom arrays in an optical cavity with dipole-dipole interactions Bao-Yun Dong(董保云), Yanhua Zhou(周彦桦), Wei Wang(王伟), and Tao Wang(汪涛) Chin. Phys. B, 2025, 34 (11):  114203.  DOI: 10.1088/1674-1056/ade388 Abstract ( 40 )   HTML ( 0 )   PDF (714KB) ( 5 )   The anisotropic Dicke model offers a platform for the exploration of numerous quantum many-body phenomena. Here, we propose a Floquet-engineered scheme to realize such a system with strong dipole-dipole interactions using Rydberg atom arrays in an optical cavity. By periodically modulating the microwave fields, the anisotropic parameter can be precisely controlled and tuned between zero and one, enabling the system to transition smoothly from being purely dominated by rotating-wave terms to being exclusively governed by counter- rotating wave excitations. Leveraging this tunability, we demonstrate enhanced preparation of adiabatic superradiant and superradiant solid phases where symmetry-protected energy gaps suppress undesired level crossings. Our approach, combining Rydberg interactions and cavity-mediated long-range correlations, establishes a versatile framework for the quantum simulation of light-matter interactions and the exploration of exotic many-body phases.

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Surface and underwater target classification under limited sample sizes based on sound field elevation structure Yixin Miao(苗艺馨), Jin Fu(付进), and Xue Wang(王雪) Chin. Phys. B, 2025, 34 (11):  114301.  DOI: 10.1088/1674-1056/ade389 Abstract ( 39 )   HTML ( 0 )   PDF (5107KB) ( 8 )   Surface/underwater target classification is a key topic in marine information research. However, the complex underwater environment, coupled with the diversity of target types and their variable characteristics, presents significant challenges for classifier design. For shallow-water waveguides with a negative thermocline, a residual neural network (ResNet) model based on the sound field elevation structure is constructed. This model demonstrates robust classification performance even when facing low signal-to-noise ratios and environmental mismatches. Meanwhile, to address the reduced generalization ability caused by limited labeled acoustic data, an improved ResNet model based on unsupervised domain adaptation (``proposed UDA-ResNet'') is further constructed. This model incorporates data on simulated elevation structures of the sound field to augment the training process. Adversarial training is employed to extract domain-invariant features from simulated and trial data. These strategies help reduce the negative impact caused by domain differences. Experimental results demonstrate that the proposed method shows strong surface/underwater target classification ability under limited sample sizes, thus confirming its feasibility and effectiveness.

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Finite element analysis of copper nanoparticles in Boger fluid: Effects of dynamic inter-particle spacing, nanolayer thermal conductivity, nanoparticles diameter, and thermal radiation over a stretching sheet Qadeer Raza, Xiaodong Wang(王晓东), Tahir Mushtaq, Bagh Ali, and Nehad Ali Shah Chin. Phys. B, 2025, 34 (11):  114402.  DOI: 10.1088/1674-1056/addcbc Abstract ( 9 )   HTML ( 0 )   PDF (21199KB) ( 1 )   This study explores the magnetohydrodynamic (MHD) boundary layer flow of a water-based Boger nanofluid over a stretching sheet, with particular focus on the influences of nanoparticle diameter, nanolayer effects, and thermal radiation. The primary aim is to examine how variations in nanoparticle size and nanolayer thickness affect the hydrothermal behavior of the nanofluid. The model also incorporates the contributions of viscous dissipation and Joule heating within the heat transfer equation. The governing momentum and energy equations are converted into dimensionless partial differential equations (PDEs) using appropriate similarity variables and are numerically solved using the finite element method (FEM) implemented in MATLAB. Extensive validation of this method confirms its reliability and accuracy in numerical solutions. The findings reveal that increasing the diameter of copper nanoparticles significantly enhances the velocity profile, with a more pronounced effect observed at wider inter-particle spacings. A higher solvent volume fraction leads to decreased velocity and temperature distributions, while a greater relaxation time ratio improves velocity and temperature profiles due to the increased elastic response of the fluid. Moreover, enhancements in the magnetic parameter, thermal radiation, and Eckert number lead to an elevation in temperature profiles. Furthermore, higher nanolayer thickness reduces the temperature profile, whereas particle radius yields the opposite outcome.

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Experimental study on characteristics of isopropanol ejection driven by electrohydrodynamics Xi-Hao Zhang(张玺皓), Wen-Hua Wang (王文华), Cheng-Nan He(何承南), Yi-Chi Yao(姚奕弛), Bo-Yu Wang (王博宇), Xue-Hong Li(李学红), Zhi-Jian Wang(王智健), Chen Qiu(邱晨), Hai-Yi Sun(孙海轶), Yu-Xin Leng(冷雨欣), and Gang Xin(新刚) Chin. Phys. B, 2025, 34 (11):  114701.  DOI: 10.1088/1674-1056/addbcc Abstract ( 13 )   HTML ( 0 )   PDF (1127KB) ( 2 )   A droplet generator is one of a key module for realizing the Sn-LPP EUV light source. One way of improving a conversion efficiency (CE) and relax tin contamination issue of Sn-LPP EUV light source is to produce tin droplet targets with suitable size. Less than several 10-μm nozzles are used to generate tin droplets. Particles from environment and chemical reaction compounds with high temperature tin cause nozzle clogging issue often. It is significant to develop a technical approach using a large diameter nozzle to produce mass-limited targets. Therefore, this paper demonstrated droplet ejection experiments based on electrohydrodynamics (EHD). Characteristics of isopropanol (IPA) droplet ejection by EHD droplet production platform that was designed and constructed in our laboratory. Characteristics of various process parameters on the IPA droplet production process were investigated. Images of droplet formation process were observed by using a droplet observation system and analyzed by image analysis software. Consequently, the smallest IPA droplet with a diameter of 13 μm could be produced using a nozzle with a diameter of 50 μm. Additionally, the EHD method could make droplets from 13 μm to 55 μm with applying voltage from 5.5 kV to 2.5 kV. In the future, EHD will apply to make mass-limited tin droplet targets under vacuum and high-temperature conditions, in order to increase the CE and to decrease tin debris.

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Spectral quasilinearization analysis of Casson fluid flow over a convectively heated inclined plate considering thermal dispersion and nonlinear thermal convection Sathyendar Sreepada, Surender Ontela, and Padigepati Naveen Chin. Phys. B, 2025, 34 (11):  114702.  DOI: 10.1088/1674-1056/ae07a9 Abstract ( 38 )   HTML ( 0 )   PDF (1116KB) ( 4 )   The present study investigates the influence of thermal dispersion on the natural convective flow of a Casson fluid along an inclined plate embedded in a non-Darcy porous medium. The governing equations, representing momentum and energy conservations, are transformed into non-dimensional form using similarity transformations. To address the complexity of the resulting equations, a bivariate spectral quasilinearisation method is employed. The effects of relevant parameters - including thermal dispersion, Casson parameter, Biot number, Forchheimer number, inclination angle and nonlinear thermal convection parameter - are thoroughly examined. The results show that the drag coefficient and heat transfer rate increase with the nonlinear thermal convection parameter, Casson parameter and Biot number. In contrast, they decrease as the Forchheimer number and inclination angle increase. The velocity near the surface of the inclined plate increases with the Biot number, Casson parameter and nonlinear thermal convection parameter. However, it decreases farther from the plate. Additionally, the temperature of the Casson fluid increases with most parameters, except the Casson and nonlinear thermal convection parameters.

PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

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One-dimensional theoretical analysis on charged-particle transports in a decaying plasma with an initial plasma-electrode gap Xin-Li Sun(孙鑫礼), Yao-Ting Wang(汪耀庭), Lan-Yue Luo(罗岚月), Zi-Ming Zhang(张子明), Meng-Long Zhang(张梦龙), He-Ping Li(李和平), Dong-Jun Jiang(姜东君), and Ming-Sheng Zhou(周明胜) Chin. Phys. B, 2025, 34 (11):  115201.  DOI: 10.1088/1674-1056/ade385 Abstract ( 29 )   HTML ( 0 )   PDF (1852KB) ( 4 )   An analytical model for describing the charged-particle transport in a wall-confined laser-induced decaying plasma is established under an external electrostatic field, focusing on the effects of the initial plasma-electrode gap (IPEG) that exists in applications such as laser isotope separation. This newly developed analytical model is validated by particle-in-cell simulations and the experimental scaling relation, and can also be reduced to its previously published counterpart that did not consider IPEGs. Based on this analytical model, the influences of different IPEG spacings on the characteristics of the whole ion extraction process are studied. The results show that the ion extraction ratios at the endpoints of the first and second stages both decrease with increasing IPEG spacing, while the corresponding time durations for the first two stages show a non-monotonous variation trend. The specific ion extraction time, defined as the ion extraction time per unit mass to comprehensively characterize the ion extraction efficiency, increases generally with the increase of IPEG spacing. This study not only provides further insight into the fundamental physical processes in a wall-bounded decaying plasma under an externally applied electrostatic field, but also offers useful theoretical guidance for optimal designs of geometrical and operating parameters in laser isotope separation processes.

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Dependence of Rayleigh-Taylor instability of finite-thickness shell on initial perturbed wavelengths Hong-Yu Guo(郭宏宇), Ben-Jin Guan(关本金), Li-Feng Wang(王立锋), Zhi-Yuan Li(李志远), and Ying-Jun Li(李英骏) Chin. Phys. B, 2025, 34 (11):  115202.  DOI: 10.1088/1674-1056/ade06b Abstract ( 12 )   HTML ( 0 )   PDF (3771KB) ( 2 )   Rayleigh-Taylor instability (RTI) of finite-thickness shell significantly impacts shell deformation and material mixing processes, with crucial implications for inertial confinement fusion (ICF). This study focuses on the RTI growth at the dual interfaces of a thin shell. A second-order weakly nonlinear (WN) analytical theory is developed to investigate the nonlinear deformation of the shell induced by different perturbation wavelengths initially imposed at the upper and lower interfaces. The validity of the theoretical results within the WN regime has been confirmed via two-dimensional Eulerian numerical simulations. Due to the interface coupling effect, the initially imposed single-mode perturbations at the upper and lower interfaces progressively evolve, exhibiting characteristics typical of multi-mode perturbations. When the initial perturbation wavelengths differ significantly, the primary structure of RTI retains its integrity, a behavior attributed to the dominance of long-wavelength perturbations. For comparable initial wavelengths, mode-coupling significantly distorts the bubble-spike structure in RTI, with the thin shell becoming prone to rupture due to enhanced nonlinear interactions.

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Impact of mass concentration variations on plasma dynamics in a laser-ablated CH target Hafiz Muhammad Siddique, Guannan Zheng(郑冠男), Tao Tao(陶弢), Xiao-Bao Jia(贾晓宝), and Jian Zheng(郑坚) Chin. Phys. B, 2025, 34 (11):  115203.  DOI: 10.1088/1674-1056/addcd0 Abstract ( 8 )   HTML ( 0 )   PDF (3462KB) ( 2 )   Laser-produced plasmas in the field of inertial confinement fusion usually consist of multiple ion species with different atomic numbers and charge-to-mass ratios. With the presence of various plasma gradients, ion diffusion is driven, causing ion concentration to evolve and deviate from its initial value. In order to investigate the effect of ion diffusion on laser-produced plasmas, we implement an ion diffusion module within the radiation-hydro code MULTI-1D [Comput. Phys. Commun. 203 226 (2016)]. Under the planar target geometry and simulation parameters considered in this study, ion species separation primarily occurs near ablation front and underdense region. Although ion diffusion just has a slight impact on plasma hydrodynamics such as density, temperature and pressure profiles, it could have significant influence on the processes in relevant to ion-acoustic wave, whose damping rate depends sensitively on ion concentration. It is found that the coupling factor of cross-beam energy transfer (CBET) could change a lot when ion diffusion is taken into account, indicating that ion diffusion could play important role in laser fusion.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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Second-order topological insulator in twisted bilayer graphene with small twist angles Fenghua Qi(戚凤华), Jie Cao(曹杰), Xingfei Zhou(周兴飞), and Guojun Jin(金国钧) Chin. Phys. B, 2025, 34 (11):  116801.  DOI: 10.1088/1674-1056/adee03 Abstract ( 21 )   HTML ( 0 )   PDF (6470KB) ( 2 )   In recent years, the study of higher-order topological states and their material realizations has become a research frontier in topological condensed matter physics. We demonstrate that twisted bilayer graphene with small twist angles behaves as a second-order topological insulator possessing topological corner charges. Using a tight-binding model, we compute the topological band indices and corner states of finite-sized twisted bilayer graphene flakes. It is found that for any small twist angle, whether commensurate or incommensurate, the gaps both below and above the flat bands are associated with nontrivial topological indices. Our results not only extend the concept of second-order band topology to arbitrary small twist angles but also confirm the existence of corner states at acute-angle corners.

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

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Swarm-intelligent predictions of high-TC polymorphs in monolayer CrI3 above 77 K Ying Luo(罗颖), Shuangyi Xu(许双旖), Yanan Wang(王亚南), and Yunwei Zhang(张云蔚) Chin. Phys. B, 2025, 34 (11):  117105.  DOI: 10.1088/1674-1056/addbcb Abstract ( 22 )   HTML ( 0 )   PDF (1466KB) ( 4 )   Monolayer CrI$_{3}$, crystalizing in the $P\bar{3}$1$m$ space group, is a prototypical two-dimensional (2D) material for observing intrinsic ferromagnetic order. However, its relatively low Curie temperature ($T_{\rm C}$) of 45 K severely limits its practical applications, highlighting the need to explore novel metastable polymorphs with enhanced magnetic properties. In this study, we employ a global crystal structure search technique combined with first-principles calculations to systematically investigate new monolayer CrI$_{3}$ phases. Our structural predictions identify two novel polymorphs with Cm and $P2/m$ space groups, both of which are dynamically stable and exhibit significantly higher $T_{\rm C}$ values of 145 K and 81 K, respectively. Electronic property calculations show that the Cm phase is a half-metal, while the $P2/m$ phase is semiconducting with a bandgap of 0.14 eV. Monte Carlo simulations attribute these enhanced $T_{\rm C}$ values to a notable increase in exchange interactions. These findings expand the known phase space of CrI$_{3}$ and provide a promising pathway for designing high-temperature 2D ferromagnets for next-generation spintronic applications.

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Intrinsic higher-order topological states in two-dimensional honeycomb quantum spin Hall insulators Sibin Lü(吕思彬) and Jun Hu(胡军) Chin. Phys. B, 2025, 34 (11):  117303.  DOI: 10.1088/1674-1056/addcd2 Abstract ( 21 )   HTML ( 0 )   PDF (3409KB) ( 2 )   The exploration of topological phases remains a cutting-edge research frontier, driven by their promising potential for next-generation electronic and quantum technologies. In this work, we employ first-principles calculations and tight-binding modeling to systematically investigate the topological properties of freestanding two-dimensional (2D) honeycomb Bi, HgTe, and Al$_{2}$O$_{3}$(0001)-supported HgTe. Remarkably, all three systems exhibit coexistence of intrinsic first- and higher-order topological insulator states, induced by spin-orbit coupling (SOC). These states manifest as topologically protected gapless edge states in one-dimensional (1D) nanoribbons and symmetry-related corner states in zero-dimensional (0D) nanoflakes. Furthermore, fractional electron charges may accumulate at the corners of armchair-edged nanoflakes. Among these materials, HgTe/Al$_{2}$O$_{3}$(0001) is particularly promising due to its experimentally feasible atomic configuration and low-energy corner states. Our findings highlight the importance of exploring higher-order topological phases in quantum spin Hall insulators and pave the way for new possibilities in device applications.

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A convenient ultrasonic path for van der Waals heterostructure construction: Study on MoS2/graphene as an example Wen Zhang(张文), Mingyang Gao(高铭阳), Jun Guo(郭俊), Licun Fu(付立存), Ling Liu(刘玲), Jing Wang(王京), and Teng Ma(马腾) Chin. Phys. B, 2025, 34 (11):  117304.  DOI: 10.1088/1674-1056/ade4ae Abstract ( 28 )   HTML ( 0 )   PDF (1006KB) ( 11 )   Ultrasound is a powerful tool in materials processing, yet its application in constructing van der Waals (vdW) heterostructures remains under-explored. In this study, MoS$_{2}$ and graphene - two widely studied 2D materials - were successfully assembled into vdW heterostructures via a convenient ultrasound-driven self-assembly approach. The morphology of the heterostructures was characterized by scanning electron microscopy (SEM), while their structural and compositional features were confirmed through x-ray diffraction (XRD), Raman spectroscopy, and x-ray photoelectron spectroscopy (XPS). Red-shifted Raman peaks and decreased binding energies in XPS spectra provided strong evidence of successful heterostructure formation. A three-stage assembly mechanism - comprising dispersion, assembly, and adjustment - is proposed, with acoustic cavitation playing a key role in driving the process. This study not only demonstrates the feasibility of synthesizing 2D heterostructures via an ultrasonic route but also lays a foundation for future scalable, energy-efficient fabrication strategies.

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Lithium-intercalation-induced structural evolution and superconductivity modulation in 2H-LixTaSe2 Lijia Zhou(周立佳), Xiangjiang Dong(董祥江), Qiang Li(李强), Xiaojun Kuang(匡小军), and Xianran Xing(邢献然) Chin. Phys. B, 2025, 34 (11):  117402.  DOI: 10.1088/1674-1056/ade24f Abstract ( 28 )   HTML ( 0 )   PDF (1634KB) ( 42 )   We systematically investigated the structural and superconducting properties of polycrystalline 2H-Li$_{x}$TaSe$_{2}$ ($0.1 \le x \le 1.0$) synthesized via a high-temperature solid-state reaction. Lithium (Li) intercalation induces an expansion along the $c$-axis and intralayer distortions within the Ta-Se coordination network. The superconducting transition temperature ($T_{\rm c}$) is increased to 2.95 K at $x = 0.1$ driven by the synergistic enhancement of the electronic density of states at the Fermi level, $N(E_{\rm F})$, and strengthened electron-phonon coupling. With further Li doping, although $N(E_{\rm F})$ continues to increase, lattice stiffening and pronounced distortions in the Ta-Se coordination polyhedra weaken the electron-phonon interaction, ultimately suppressing superconductivity. These findings highlight the critical role of intralayer structural modulation in governing structure-tunable superconductivity in layered materials.

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Coupling between phonon and short-range spin correlations in frustrated spinel LiFeCr4O8 Xiang Li(李想), Wei Ren(任玮), Bo Zhang(张博), Yan-Zhen Cai(蔡焱桢), Zhi-Wei Li(李志伟), Jianting Ji(籍建葶), Feng Jin(金峰), Anmin Zhang(张安民), and Qingming Zhang(张清明) Chin. Phys. B, 2025, 34 (11):  117801.  DOI: 10.1088/1674-1056/ade4b4 Abstract ( 34 )   HTML ( 0 )   PDF (1748KB) ( 14 )   Spin-phonon coupling is important in chromate spinel oxides $A$Cr$_2$O$_4$, but its role in LiFeCr$_4$O$_8$ is not well understood. In this paper, we employ Raman scattering and first-principles phonon calculations to study this material. Ten out of 13 Raman-active modes are well assigned. Notably, no phonon splitting is observed across the structural phase transition due to the remarkably small Grüneisen constants. This observation, in conjunction with the structural data, provides compelling evidence that the structural phase transition in LiFeCr$_4$O$_8$ is primarily driven by the spin-driven Jahn-Teller effect. Interestingly, some Raman modes (at 207 cm$^{-1}$, 306 cm$^{-1}$ and 462 cm$^{-1}$) exhibit unusual linewidth behavior across the temperature range investigated. Furthermore, the Raman spectra in different phases show no magnetic field dependence. These results suggest that phonons couple with short-range spin correlations, offering insights into how spin and lattice degrees of freedom interact in frustrated systems.

INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY

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Regulation mechanism of Si vacancies in unintentional silicon-doped diamond by gas flow in MPCVD Kai Yang(杨凯), Liangxue Gu(顾梁雪), Gengyou Zhao(赵耕右), Kun Tang(汤琨), Bo Feng(冯博), Jiandong Ye(叶建东), Rong Zhang(张荣), Shunming Zhu(朱顺明), and Shulin Gu(顾书林) Chin. Phys. B, 2025, 34 (11):  118102.  DOI: 10.1088/1674-1056/ae07aa Abstract ( 61 )   HTML ( 0 )   PDF (5576KB) ( 14 )   Diamond with silicon vacancies has an important role as a promising single-photon source applicable in the quantum information field. However, in a microwave plasma chemical vapor deposition (MPCVD) system, due to the presence of unintentional silicon doping sources such as quartz windows, the behavior of silicon vacancy formation in silicon-doped diamond is complex. In this work, the underlying mechanism of formation of silicon vacancies by unintentional silicon doping in diamond is investigated from the perspective of growing surface kinetics in a two-gas-flow MPCVD system. This system is equipped with a novel susceptor geometry designed to deliver an additional gas flow directly onto the substrate surface. Increasing the concentration of growth doping substances on the substrate surface thereby enhances the efficiency of silicon vacancy formation in diamond. At the same time, by changing the substrate deposition angle the distribution of gas and plasma on the substrate surface is changed, thereby regulating the concentration and distribution of silicon vacancies formed by unintentional silicon doping. Experimental and computational results demonstrate that the difference in silicon vacancies formed by unintentional silicon doping in diamond depends on the substances present on the substrate surface and the distribution of plasma.

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The 5-THz metal-mesh filters based on Mylar film Qiang Zhi(支强), Jiameng Wang(王家萌), Wei Geng(耿伟), Yuhao Hu(胡雨浩), Hao Wu(吴昊), Kangmin Zhou(周康敏), Jiangqiao Ding(丁江乔), Jie Hu(胡洁), Zheng Wang(王争), Wei Miao(缪巍), Jing Li(李婧), and Shengcai Shi(史生才) Chin. Phys. B, 2025, 34 (11):  118401.  DOI: 10.1088/1674-1056/addbca Abstract ( 15 )   HTML ( 0 )   PDF (1306KB) ( 2 )   Imaging detector arrays have been widely used in terahertz (THz) astronomical observations, where optical filters play an important role. In this work, a 5-THz metal-mesh bandpass filter (MMBF) using cross-slot-shaped resonators is developed and fabricated on Mylar film through photolithography. Extensive simulations, accounting for factors such as Mylar film loss, surface conductivity, corner errors, and surface roughness, were conducted to assess their impact on the filter's performance. The measured characteristics, including a center frequency of 5.06 THz, a transmittance of 62%, and a 3-dB fractional bandwidth (FBW) is 38%, obtained via Fourier-transform infrared spectroscopy (FTIR), closely match the simulation results. This scalable metal-mesh filter shows promise for future THz astronomical applications.

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Degradation mechanisms of Schottky p-GaN gate AlGaN/GaN HEMTs under high-temperature reverse bias stress Fei Hu(胡飞), Chengbing Pan(潘成兵), Xinyuan Zheng(郑鑫源), Yibo Ning(宁一博), Xueyan Li(李雪燕), and Lixia Zhao(赵丽霞) Chin. Phys. B, 2025, 34 (11):  118501.  DOI: 10.1088/1674-1056/ade1c0 Abstract ( 37 )   HTML ( 0 )   PDF (1014KB) ( 44 )   The degradation mechanisms of Schottky p-GaN gate AlGaN/GaN HEMTs under high-temperature reverse bias (HTRB) stress were investigated and the evolution of the deep traps was identified using deep-level transient spectroscopy. The saturation current of p-GaN gate AlGaN/GaN HEMTs decreased by 18.2% and the threshold voltage shifted positively by 11.6% after the degradation. An electron trap (at 369 K) and a hole trap (at 95 K) were observed in the AlGaN/GaN region, while another hole trap (at 359 K) was found in the p-GaN layer before the stress. Meanwhile, after the stress, the concentration and capture cross section of the hole traps increased in both the p-GaN layer and the AlGaN/GaN region. With regard to the electron trap in the AlGaN/GaN region, the capture cross section increased significantly but the electron trap concentration slightly decreased, which may increase the electron trapping, thereby reducing electrons in the two-dimensional electron gas. These factors result in a positive shift in the threshold voltage and a decrease in the output current. This work provides a new insight into understanding the threshold voltage instability of Schottky p-GaN gate AlGaN/GaN HEMTs.

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Coupled dynamics of information diffusion and disease transmission considering vaccination and time-varying forgetting probability Lai-Jun Zhao(赵来军), Lu-Ping Chen(陈陆平), Ping-Le Yang(杨平乐), Fan-Yuan Meng(孟凡圆), and Chen Dong(董晨) Chin. Phys. B, 2025, 34 (11):  118701.  DOI: 10.1088/1674-1056/ade067 Abstract ( 8 )   HTML ( 0 )   PDF (956KB) ( 3 )   Vaccination is critical for controlling infectious diseases, but negative vaccination information can lead to vaccine hesitancy. To study how the interplay between information diffusion and disease transmission impacts vaccination and epidemic spread, we propose a novel two-layer multiplex network model that integrates an unaware-acceptant-negative-unaware (UANU) information diffusion model with a susceptible-vaccinated-exposed-infected-susceptible (SVEIS) epidemiological framework. This model includes individual exposure and vaccination statuses, time-varying forgetting probabilities, and information conversion thresholds. Through the microscopic Markov chain approach (MMCA), we derive dynamic transition equations and the epidemic threshold expression, validated by Monte Carlo simulations. Using MMCA equations, we predict vaccination densities and analyze parameter effects on vaccination, disease transmission, and the epidemic threshold. Our findings suggest that promoting positive information, curbing the spread of negative information, enhancing vaccine effectiveness, and promptly identifying asymptomatic carriers can significantly increase vaccination rates, reduce epidemic spread, and raise the epidemic threshold.

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Effect of 3.1-THz radiation on pathological progression in Caenorhabditis elegans Alzheimer’s disease model Lei Wang(王磊), Meng Wang(王萌), Xumei Zhang(张绪梅), and Mingxia He(何明霞) Chin. Phys. B, 2025, 34 (11):  118702.  DOI: 10.1088/1674-1056/ade06a Abstract ( 17 )   HTML ( 0 )   PDF (1659KB) ( 3 )   Terahertz (THz) radiation, an emerging frequency band of the electromagnetic spectrum, has been widely applied across various fields. However, its ability to resonate with the energy levels of biomolecules has raised significant concerns regarding its biosafety. A growing body of research indicates that THz radiation can markedly influence the structure and function of proteins. Alzheimer's disease (AD), a neurodegenerative disorder characterized by the abnormal aggregation of amyloid proteins, has been shown in prior studies to be modulated by THz radiation in terms of amyloid aggregation. Building on this, the present study utilized the CL4176 strain of Caenorhabditis elegans as an animal model for AD. Using a self-designed and constructed radiation system based on quantum cascade lasers, the study investigated changes in the pathological progression of AD under 3.1-THz electromagnetic radiation exposure. By evaluating lifespan, motility, feeding behavior, reactive oxygen species (ROS) levels, and aging markers in the Caenorhabditis elegans model, the study highlights the potential biological risks of 3.1-THz radiation for individuals with AD. These findings provide crucial experimental evidence to support the promotion and standardization of THz technology applications.

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Thorough numerical simulations of silicon heterojunction solar cells focusing on the sun-side-doped layer Jiufang Han(韩久放), Yimeng Song(宋祎萌), Xiran Yu(于夕然), Conghui Jiang(姜聪慧), Wenxin Wang(王文新), Haiqiang Jia(贾海强), Chunhua Du(杜春花), and Hong Chen(陈弘) Chin. Phys. B, 2025, 34 (11):  118801.  DOI: 10.1088/1674-1056/addcc4 Abstract ( 20 )   HTML ( 1 )   PDF (1165KB) ( 4 )   To improve the photovoltaic conversion efficiency (PCE) of silicon heterojunction (SHJ) solar cells, this study focuses on optimizing the physical parameters of the sun-side-doped layer and proposes strategies to address the challenges posed by Fermi level pinning in wide bandgap designs. Using AFORS-HET simulations, we systematically investigate the effects of bandgap width, doping concentration, and defect state distribution on the energy band structure, interface electric field, and carrier transport dynamics. The results reveal that maintaining the Fermi level within 0.3 eV of the conduction band is essential for optimal device performance. A wider bandgap (> 1.8 eV) enhances the utilization of short-wavelength light and significantly suppresses interface recombination, leading to an increase in short-circuit current density ($J_{\rm sc}$) by 0.8 mA/cm$^2$. This benefit comes with a delicate balance between minimizing defect state density and improving doping efficiency. This study provides theoretical insights into the optimization of doped layer physical parameters and proposes practical solutions, including nano-crystallization and low-doping interface strategies, to improve the performance of SHJ solar cells and support industrial applications.