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Controlling the dynamic behavior of decentralized cluster through centralized approaches Daming Yuan(袁大明), Peilong Wang(王培龙), Peng Wang(王鹏), Xingyu Ma(马星宇), Chuyun Wang(汪楚云), Jing Wang(王璟), Huaicheng Chen(陈怀城), Gao Wang(王高), and Fangfu Ye(叶方富) Chin. Phys. B, 2024, 33 (6): 060702.   DOI: 10.1088/1674-1056/ad3dd0 Abstract （143）      PDF （3679KB）（101）       Knowledge map    How to control the dynamic behavior of large-scale artificial active matter is a critical concern in experimental research on soft matter, particularly regarding the emergence of collective behaviors and the formation of group patterns. Centralized systems excel in precise control over individual behavior within a group, ensuring high accuracy and controllability in task execution. Nevertheless, their sensitivity to group size may limit their adaptability to diverse tasks. In contrast, decentralized systems empower individuals with autonomous decision-making, enhancing adaptability and system robustness. Yet, this flexibility comes at the cost of reduced accuracy and efficiency in task execution. In this work, we present a unique method for regulating the centralized dynamic behavior of self-organizing clusters based on environmental interactions. Within this environment-coupled robot system, each robot possesses similar dynamic characteristics, and their internal programs are entirely identical. However, their behaviors can be guided by the centralized control of the environment, facilitating the accomplishment of diverse cluster tasks. This approach aims to balance the accuracy and flexibility of centralized control with the robustness and task adaptability of decentralized control. The proactive regulation of dynamic behavioral characteristics in active matter groups, demonstrated in this work through environmental interactions, holds the potential to introduce a novel technological approach and provide experimental references for studying the dynamic behavior control of large-scale artificial active matter systems.

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Field induced Chern insulating states in twisted monolayer-bilayer graphene Zhengwen Wang(王政文), Yingzhuo Han(韩英卓), Kenji Watanabe, Takashi Taniguchi, Yuhang Jiang(姜宇航), and Jinhai Mao(毛金海) Chin. Phys. B, 2024, 33 (6): 067301.   DOI: 10.1088/1674-1056/ad3b8a Abstract （89）      PDF （1262KB）（71）       Knowledge map    Unraveling the mechanism underlying topological phases, notably the Chern insulators (ChIs) in strong correlated systems at the microscopy scale, has captivated significant research interest. Nonetheless, ChIs harboring topological information have not always manifested themselves, owing to the constraints imposed by displacement fields in certain experimental configurations. In this study, we employ density-tuned scanning tunneling microscopy (DT-STM) to investigate the ChIs in twisted monolayer-bilayer graphene (tMBG). At zero magnetic field, we observe correlated metallic states. While under a magnetic field, a metal-insulator transition happens and an integer ChI is formed emanating from the filling index $ s = 3$ with a Chern number $C = 1$. Our results underscore the pivotal role of magnetic fields as a powerful probe for elucidating topological phases in twisted Van der Waals heterostructures.

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Relationship between disorder, magnetism and band topology in Mn(Sb1-xBix)2Te4 single crystals Ming Xi(席明) and Hechang Lei(雷和畅) Chin. Phys. B, 2024, 33 (6): 067503.   DOI: 10.1088/1674-1056/ad3dd8 Abstract （73）      PDF （919KB）（75）       Knowledge map    We investigate the evolution of magnetic properties as well as the content and distribution of Mn for Mn(Sb$_{1-x}$Bi$_{x}$)$_{2}$Te$_{4}$ single crystals grown by large-temperature-gradient chemical vapor transport method. It is found that the ferromagnetic MnSb$_{2}$Te$_{4}$ changes to antiferromagnetism with Bi doping when $x \ge 0.25$. Further analysis implies that the occupations of Mn ions at Sb/Bi site Mn$_{\rm Sb/Bi}$ and Mn site Mn$_{\rm Mn}$ have a strong influence on the magnetic ground states of these systems. With the decrease of Mn$_{\rm Mn}$ and increase of Mn$_{\rm Sb/Bi}$, the system will favor the ferromagnetic ground state. In addition, the rapid decrease of $T_{\rm C/N}$ with increasing Bi content when $x \le 0.25$ and the insensitivity of $T_{\rm N}$ to $x$ when $x > 0.25$ suggest that the main magnetic interaction may change from the Ruderman-Kittel-Kasuya-Yosida type at low Bi doping region to the van-Vleck type in high Bi doped samples.

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Unveiling the pressure-driven metal-semiconductor-metal transition in the doped TiS2 Jiajun Chen(陈佳骏), Xindeng Lv(吕心邓), Simin Li(李思敏), Yaqian Dan(但雅倩), Yanping Huang(黄艳萍), and Tian Cui(崔田) Chin. Phys. B, 2024, 33 (6): 067104.   DOI: 10.1088/1674-1056/ad4325 Abstract （67）      PDF （1175KB）（68）       Knowledge map    Conventional theories expect that materials under pressure exhibit expanded valence and conduction bands, leading to increased electrical conductivity. Here, we report the electrical properties of the doped 1$T$-TiS$_{2}$ under high pressure by electrical resistance investigations, synchrotron x-ray diffraction, Raman scattering and theoretical calculations. Up to 70GPa, an unusual metal-semiconductor-metal transition occurs. Our first-principles calculations suggest that the observed anti-Wilson transition from metal to semiconductor at 17GPa is due to the electron localization induced by the intercalated Ti atoms. This electron localization is attributed to the strengthened coupling between the doped Ti atoms and S atoms, and the Anderson localization arising from the disordered intercalation. At pressures exceeding 30.5GPa, the doped TiS$_{2}$ undergoes a re-metallization transition initiated by a crystal structure phase transition. We assign the most probable space group as $P$2$_{1}$2$_{1}$2$_{1}$. Our findings suggest that materials probably will eventually undergo the Wilson transition when subjected to sufficient pressure.

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One memristor-one electrolyte-gated transistor-based high energy-efficient dropout neuronal units Yalin Li(李亚霖), Kailu Shi(时凯璐), Yixin Zhu(朱一新), Xiao Fang(方晓), Hangyuan Cui(崔航源), Qing Wan(万青), and Changjin Wan(万昌锦) Chin. Phys. B, 2024, 33 (6): 068401.   DOI: 10.1088/1674-1056/ad39d6 Abstract （42）      PDF （923KB）（17）       Knowledge map    Artificial neural networks (ANN) have been extensively researched due to their significant energy-saving benefits. Hardware implementations of ANN with dropout function would be able to avoid the overfitting problem. This letter reports a dropout neuronal unit (1R1T-DNU) based on one memristor-one electrolyte-gated transistor with an ultralow energy consumption of 25pJ/spike. A dropout neural network is constructed based on such a device and has been verified by MNIST dataset, demonstrating high recognition accuracies ($> 90$%) within a large range of dropout probabilities up to 40%. The running time can be reduced by increasing dropout probability without a significant loss in accuracy. Our results indicate the great potential of introducing such 1R1T-DNUs in full-hardware neural networks to enhance energy efficiency and to solve the overfitting problem.

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Semiclassical approach to spin dynamics of a ferromagnetic S=1 chain Chengchen Li(李承晨), Yi Cui(崔祎), Weiqiang Yu(于伟强), and Rong Yu(俞榕) Chin. Phys. B, 2024, 33 (6): 067501.   DOI: 10.1088/1674-1056/ad3c32 Abstract （45）      PDF （1107KB）（31）       Knowledge map    Motivated by recent experimental progress on the quasi-one-dimensional quantum magnet NiNb$_2$O$_6$, we study the spin dynamics of an $S=1$ ferromagnetic Heisenberg chain with single-ion anisotropy by using a semiclassical molecular dynamics approach. This system undergoes a quantum phase transition from a ferromagnetic to a paramagnetic state under a transverse magnetic field, and the magnetic response reflecting this transition is well described by our semiclassical method. We show that at low temperature the transverse component of the dynamical structure factor depicts clearly the magnon dispersion, and the longitudinal component exhibits two continua associated with single- and two-magnon excitations, respectively. These spin excitation spectra show interesting temperature dependence as effects of magnon interactions. Our findings shed light on the experimental detection of spin excitations in a large class of quasi-one-dimensional magnets.

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Layered kagome compound Na2Ni3S4 with topological flat band Junyao Ye(叶君耀), Yihao Lin(林益浩), Haozhe Wang(王浩哲), Zhida Song(宋志达), Ji Feng(冯济), Weiwei Xie(谢韦伟), and Shuang Jia(贾爽) Chin. Phys. B, 2024, 33 (5): 057103.   DOI: 10.1088/1674-1056/ad3431 Abstract （288）   HTML （14）    PDF （2643KB）（266）       Knowledge map    We report structural and electronic properties of Na$_2$Ni$_3$S$_4$, a quasi-two-dimensional compound composed of alternating layers of [Ni$_3$S$_4$]$^{2-}$ and Na$^{+}$. The compound features a remarkable Ni-based kagome lattice with a square planar configuration of four surrounding S atoms for each Ni atom. Magnetization and electrical measurements reveal a weak paramagnetic insulator with a gap of about 0.5 eV.Our band structure calculation highlights a set of topological flat bands of the kagome lattice derived from the rotated d$_{xz}$-orbital with $C_\mathrm{3}$ + $T$ symmetry in the presence of crystal-field splitting.

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Nonreciprocal transport in the superconducting state of the chiral crystal NbGe2 Yonglai Liu(刘永来), Xitong Xu(许锡童), Miao He(何苗), Haitian Zhao(赵海天), Qingqi Zeng(曾庆祺), Xingyu Yang(杨星宇), Youming Zou(邹优鸣), Haifeng Du(杜海峰), and Zhe Qu(屈哲) Chin. Phys. B, 2024, 33 (5): 057402.   DOI: 10.1088/1674-1056/ad334b Abstract （154）   HTML （11）    PDF （2451KB）（139）       Knowledge map    Due to the lack of inversion, mirror or other roto-inversion symmetries, chiral crystals possess a well-defined handedness which, when combined with time-reversal symmetry breaking from the application of magnetic fields, can give rise to directional dichroism of the electrical transport phenomena via the magnetochiral anisotropy. In this study, we investigate the nonreciprocal magneto-transport in microdevices of NbGe$_{2}$, a superconductor with structural chirality. A giant nonreciprocal signal from vortex motions is observed during the superconducting transition, with the ratio of nonreciprocal resistance to the normal resistance ${\gamma}$ reaching 6$\times10^{5}$~T$^{-1}$$\cdot$A$^{-1}$. Interestingly, the intensity can be adjusted and even sign-reversed by varying the current, the temperature, and the crystalline orientation. Our findings illustrate intricate vortex dynamics and offer ways of manipulation on the rectification effect in superconductors with structural chirality.

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Estimation of cancer cell migration in biomimetic random/oriented collagen fiber microenvironments Jingru Yao(姚静如), Guoqiang Li(李国强), Xiyao Yao(姚喜耀), Lianjie Zhou(周连杰), Zhikai Ye(叶志凯), Yanping Liu(刘艳平), Dongtian Zheng(郑栋天), Ting Tang(唐婷), Kena Song(宋克纳), Guo Chen(陈果), and Liyu Liu(刘雳宇) Chin. Phys. B, 2024, 33 (5): 058706.   DOI: 10.1088/1674-1056/ad334c Abstract （99）   HTML （4）    PDF （3033KB）（117）       Knowledge map    Increasing data indicate that cancer cell migration is regulated by extracellular matrixes and their surrounding biochemical microenvironment, playing a crucial role in pathological processes such as tumor invasion and metastasis. However, conventional two-dimensional cell culture and animal models have limitations in studying the influence of tumor microenvironment on cancer cell migration. Fortunately, the further development of microfluidic technology has provided solutions for the study of such questions. We utilize microfluidic chip to build a random collagen fiber microenvironment (RFM) model and an oriented collagen fiber microenvironment (OFM) model that resemble early stage and late stage breast cancer microenvironments, respectively. By combining cell culture, biochemical concentration gradient construction, and microscopic imaging techniques, we investigate the impact of different collagen fiber biochemical microenvironments on the migration of breast cancer MDA-MB-231-RFP cells. The results show that MDA-MB-231-RFP cells migrate further in the OFM model compared to the RFM model, with significant differences observed. Furthermore, we establish concentration gradients of the anticancer drug paclitaxel in both the RFM and OFM models and find that paclitaxel significantly inhibits the migration of MDA-MB-231-RFP cells in the RFM model, with stronger inhibition on the high concentration side compared to the low concentration side. However, the inhibitory effect of paclitaxel on the migration of MDA-MB-231-RFP cells in the OFM model is weak. These findings suggest that the oriented collagen fiber microenvironment resembling the late-stage tumor microenvironment is more favorable for cancer cell migration and that the effectiveness of anticancer drugs is diminished. The RFM and OFM models constructed in this study not only provide a platform for studying the mechanism of cancer development, but also serve as a tool for the initial measurement of drug screening.

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Dynamical localization in a non-Hermitian Floquet synthetic system Han Ke(可汗), Jiaming Zhang(张嘉明), Liang Huo(霍良), and Wen-Lei Zhao(赵文垒) Chin. Phys. B, 2024, 33 (5): 050507.   DOI: 10.1088/1674-1056/ad36bb Abstract （93）   HTML （4）    PDF （761KB）（116）       Knowledge map    We investigate the non-Hermitian effects on quantum diffusion in a kicked rotor model where the complex kicking potential is quasi-periodically modulated in the time domain. The synthetic space with arbitrary dimension can be created by incorporating incommensurate frequencies in the quasi-periodical modulation. In the Hermitian case, strong kicking induces the chaotic diffusion in the four-dimension momentum space characterized by linear growth of mean energy. We find that the quantum coherence in deep non-Hermitian regime can effectively suppress the chaotic diffusion and hence result in the emergence of dynamical localization. Moreover, the extent of dynamical localization is dramatically enhanced by increasing the non-Hermitian parameter. Interestingly, the quasi-energies become complex when the non-Hermitian parameter exceeds a certain threshold value. The quantum state will finally evolve to a quasi-eigenstate for which the imaginary part of its quasi-energy is large most. The exponential localization length decreases with the increase of the non-Hermitian parameter, unveiling the underlying mechanism of the enhancement of the dynamical localization by non-Hermiticity.

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Electronic structure and effective mass of pristine and Cl-doped CsPbBr3 Zhiyuan Wei(魏志远), Yu-Hao Wei(魏愉昊), Shendong Xu(徐申东), Shuting Peng(彭舒婷), Makoto Hashimoto, Donghui Lu(路东辉), Xu Pan(潘旭), Min-Quan Kuang(匡泯泉), Zhengguo Xiao(肖正国), and Junfeng He(何俊峰) Chin. Phys. B, 2024, 33 (5): 057403.   DOI: 10.1088/1674-1056/ad3c31 Abstract （84）   HTML （2）    PDF （5143KB）（56）       Knowledge map    Organic-inorganic lead halide perovskites (LHPs) have attracted great interest owing to their outstanding optoelectronic properties. Typically, the underlying electronic structure would determinate the physical properties of materials. But as for now, limited studies have been done to reveal the underlying electronic structure of this material system, comparing to the huge amount of investigations on the material synthesis. The effective mass of the valance band is one of the most important physical parameters which plays a dominant role in charge transport and photovoltaic phenomena. In pristine CsPbBr$_{3}$, the Fröhlich polarons associated with the Pb-Br stretching modes are proposed to be responsible for the effective mass renormalization. In this regard, it would be very interesting to explore the electronic structure in doped LHPs. Here, we report high-resolution angle-resolved photoemission spectroscopy (ARPES) studies on both pristine and Cl-doped CsPbBr$_{3}$. The experimental band dispersions are extracted from ARPES spectra along both $\bar{\varGamma}$-$\bar{M}$-$\bar{\varGamma }$ and $\bar{X}$-$\bar{M}$-$\bar{X}$ high symmetry directions. DFT calculations are performed and directly compared with the ARPES data. Our results have revealed the band structure of Cl-doped CsPbBr$_{3}$ for the first time, which have also unveiled the effective mass renormalization in the Cl-doped CsPbBr$_{3}$ compound. Doping dependent measurements indicate that the chlorine doping could moderately tune the renormalization strength. These results will help understand the physical properties of LHPs as a function of doping.

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Symmetry transformation of nonlinear optical current of tilted Weyl nodes and application to ferromagnetic MnBi2Te4 Zhuo-Cheng Lu(卢倬成) and Ji Feng(冯济) Chin. Phys. B, 2024, 33 (4): 047303.   DOI: 10.1088/1674-1056/ad2bfb Abstract （298）   HTML （1）    PDF （2239KB）（359）       Knowledge map    A Weyl node is characterized by its chirality and tilt. We develop a theory of how nth-order nonlinear optical conductivity behaves under transformations of anisotropic tensor and tilt, which clarifies how chirality-dependent and -independent parts of optical conductivity transform under the reversal of tilt and chirality. Built on this theory, we propose ferromagnetic m MnBi2Te4 as a magnetoelectrically regulated, terahertz optical device, by magnetoelectrically switching the chirality-dependent and -independent DC photocurrents. These results are useful for creating nonlinear optical devices based on the topological Weyl semimetals.

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Coexistence of Dirac and Weyl points in non-centrosymmetric semimetal NbIrTe4 Qingxin Liu(刘清馨), Yang Fu(付阳), Pengfei Ding(丁鹏飞), Huan Ma(马欢), Pengjie Guo(郭朋杰), Hechang Lei(雷和畅), and Shancai Wang(王善才) Chin. Phys. B, 2024, 33 (4): 047104.   DOI: 10.1088/1674-1056/ad2a79 Abstract （231）   HTML （0）    PDF （2350KB）（224）       Knowledge map    Using angle-resolved photoemission spectroscopy and density functional theory calculations methods, we investigate the electronic structures and topological properties of ternary tellurides NbIrTe4, a candidate for type-II Weyl semimetal. We demonstrate the presence of several Fermi arcs connecting their corresponding Weyl points on both termination surfaces of the topological material. Our analysis reveals the existence of Dirac points, in addition to Weyl points, giving both theoretical and experimental evidences of the coexistence of Dirac and Weyl points in a single material. These findings not only confirm NbIrTe4 as a unique topological semimetal but also open avenues for exploring novel electronic devices based on its coexisting Dirac and Weyl fermions.

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Improving the electrical performances of InSe transistors by interface engineering Tianjun Cao(曹天俊), Song Hao(郝松), Chenchen Wu(吴晨晨), Chen Pan(潘晨), Yudi Dai(戴玉頔), Bin Cheng(程斌), Shi-Jun Liang(梁世军), and Feng Miao(缪峰) Chin. Phys. B, 2024, 33 (4): 047302.   DOI: 10.1088/1674-1056/ad24d7 Abstract （134）   HTML （0）    PDF （1195KB）（153）       Knowledge map    InSe has emerged as a promising candidate for next-generation electronics due to its predicted ultrahigh electrical performance. However, the efficacy of the InSe transistor in meeting application requirements is hindered due to its sensitivity to interfaces. In this study, we have achieved notable enhancement in the electrical performance of InSe transistors through interface engineering. We engineered an InSe/h-BN heterostructure, effectively suppressing dielectric layer-induced scattering. Additionally, we successfully established excellent metal—semiconductor contacts using graphene ribbons as a buffer layer. Through a methodical approach to interface engineering, our graphene/InSe/h-BN transistor demonstrates impressive on-state current, field-effect mobility, and on/off ratio at room temperature, reaching values as high as 1.1 mA/μm, 904 cm2·V-1·s-1, and >106, respectively. Theoretical computations corroborate that the graphene/InSe heterostructure shows significant interlayer charge transfer and weak interlayer interaction, contributing to the enhanced performance of InSe transistors. This research offers a comprehensive strategy to elevate the electrical performance of InSe transistors, paving the way for their utilization in future electronic applications.

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Co-doped BaFe2As2 Josephson junction fabricated with a focused helium ion beam Ziwen Chen(陈紫雯), Yan Zhang(张焱), Ping Ma(马平), Zhongtang Xu(徐中堂), Yulong Li(李宇龙), Yue Wang(王越), Jianming Lu(路建明), Yanwei Ma(马衍伟), and Zizhao Gan(甘子钊) Chin. Phys. B, 2024, 33 (4): 047405.   DOI: 10.1088/1674-1056/ad21f7 Abstract （154）   HTML （1）    PDF （1351KB）（164）       Knowledge map    Josephson junction plays a key role not only in studying the basic physics of unconventional iron-based superconductors but also in realizing practical application of thin-film based devices, therefore the preparation of high-quality iron pnictide Josephson junctions is of great importance. In this work, we have successfully fabricated Josephson junctions from Co-doped BaFe2As2 thin films using a direct junction fabrication technique which utilizes high energy focused helium ion beam (FHIB). The electrical transport properties were investigated for junctions fabricated with various He+ irradiation doses. The junctions show sharp superconducting transition around 24 K with a narrow transition width of 2.5 K, and a dose correlated foot-structure resistance which corresponds to the effective tuning of junction properties by He+ irradiation. Significant Jc suppression by more than two orders of magnitude can be achieved by increasing the He+ irradiation dose, which is advantageous for the realization of low noise ion pnictide thin film devices. Clear Shapiro steps are observed under 10 GHz microwave irradiation. The above results demonstrate the successful fabrication of high quality and controllable Co-doped BaFe2As2 Josephson junction with high reproducibility using the FHIB technique, laying the foundation for future investigating the mechanism of iron-based superconductors, and also the further implementation in various superconducting electronic devices.

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Localization effect in single crystal of RuAs2 Zhe-Kai Yi(易哲铠), Qi Liu(刘琪), Shuang-Kui Guang(光双魁), Sheng Xu(徐升), Xiao-Yu Yue(岳小宇), Hui Liang(梁慧), Na Li(李娜), Ying Zhou(周颖), Dan-Dan Wu(吴丹丹), Yan Sun(孙燕), Qiu-Ju Li(李秋菊), Peng Cheng(程鹏), Tian-Long Xia(夏天龙), Xue-Feng Sun(孙学峰), and Yi-Yan Wang(王义炎) Chin. Phys. B, 2024, 33 (4): 047501.   DOI: 10.1088/1674-1056/ad23d9 Abstract （155）   HTML （0）    PDF （2374KB）（139）       Knowledge map    We report the magnetotransport and thermal properties of RuAs2 single crystal. RuAs2 exhibits semiconductor behavior and localization effect. The crossover from normal state to diffusive transport in the weak localization (WL) state and then to variable range hopping (VRH) transport in the strong localization state has been observed. The transitions can be reflected in the measurement of resistivity and Seebeck coefficient. Negative magnetoresistance (NMR) emerges with the appearance of localization effect and is gradually suppressed in high magnetic field. The temperature dependent phase coherence length extracted from the fittings of NMR also indicates the transition from WL to VRH. The measurement of Hall effect reveals an anomaly of temperature dependent carrier concentration caused by localization effect. Our findings show that RuAs2 is a suitable platform to study the localized state.

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Image segmentation of exfoliated two-dimensional materials by generative adversarial network-based data augmentation Xiaoyu Cheng(程晓昱), Chenxue Xie(解晨雪), Yulun Liu(刘宇伦), Ruixue Bai(白瑞雪), Nanhai Xiao(肖南海), Yanbo Ren(任琰博), Xilin Zhang(张喜林), Hui Ma(马惠), and Chongyun Jiang(蒋崇云) Chin. Phys. B, 2024, 33 (3): 030703.   DOI: 10.1088/1674-1056/ad23d8 Abstract （444）   HTML （36）    PDF （1065KB）（451）       Knowledge map    Mechanically cleaved two-dimensional materials are random in size and thickness. Recognizing atomically thin flakes by human experts is inefficient and unsuitable for scalable production. Deep learning algorithms have been adopted as an alternative, nevertheless a major challenge is a lack of sufficient actual training images. Here we report the generation of synthetic two-dimensional materials images using StyleGAN3 to complement the dataset. DeepLabv3Plus network is trained with the synthetic images which reduces overfitting and improves recognition accuracy to over 90%. A semi-supervisory technique for labeling images is introduced to reduce manual efforts. The sharper edges recognized by this method facilitate material stacking with precise edge alignment, which benefits exploring novel properties of layered-material devices that crucially depend on the interlayer twist-angle. This feasible and efficient method allows for the rapid and high-quality manufacturing of atomically thin materials and devices.

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Measuring small longitudinal phase shifts via weak measurement amplification Kai Xu(徐凯), Xiao-Min Hu(胡晓敏), Meng-Jun Hu(胡孟军), Ning-Ning Wang(王宁宁), Chao Zhang(张超), Yun-Feng Huang(黄运锋), Bi-Heng Liu(柳必恒), Chuan-Feng Li(李传锋), Guang-Can Guo(郭光灿), and Yong-Sheng Zhang(张永生) Chin. Phys. B, 2024, 33 (3): 030602.   DOI: 10.1088/1674-1056/ad1c5a Abstract （226）   HTML （14）    PDF （1036KB）（323）       Knowledge map    Weak measurement amplification, which is considered as a very promising scheme in precision measurement, has been applied to various small physical quantities estimations. Since many physical quantities can be converted into phase signals, it is interesting and important to consider measuring small longitudinal phase shifts by using weak measurement. Here, we propose and experimentally demonstrate a novel weak measurement amplification-based small longitudinal phase estimation, which is suitable for polarization interferometry. We realize one order of magnitude amplification measurement of a small phase signal directly introduced by a liquid crystal variable retarder and show that it is robust to the imperfection of interference. Besides, we analyze the effect of magnification error which is never considered in the previous works, and find the constraint on the magnification. Our results may find important applications in high-precision measurements, e.g., gravitational wave detection.

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Anomalous spin Josephson effect in spin superconductors Wen Zeng(曾文) and Rui Shen(沈瑞) Chin. Phys. B, 2024, 33 (3): 037401.   DOI: 10.1088/1674-1056/ad1982 Abstract （121）   HTML （5）    PDF （634KB）（168）       Knowledge map    The spin superconductor state is the spin-polarized triplet exciton condensate, which can be viewed as a counterpart of the charge superconductor state. As an analogy of the charge Josephson effect, the spin Josephson effect can be generated in the spin superconductor/normal metal/spin superconductor junctions. Here we study the spin supercurrent in the Josephson junctions consisting of two spin superconductors with noncollinear spin polarizations. For the Josephson junctions with out-of-plane spin polarizations, the possible π-state spin supercurrent appears due to the Fermi momentum-splitting Andreev-like reflections at the normal metal/spin superconductor interfaces. For the Josephson junctions with in-plane spin polarizations, the anomalous spin supercurrent appears and is driven by the misorientation angle of the in-plane polarizations. The symmetry analysis shows that the appearance of the anomalous spin Josephson current is possible when the combined symmetry of the spin rotation and the time reversal is broken.

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Creation and annihilation of artificial magnetic skyrmions with the electric field Jun Cheng(程军), Liang Sun(孙亮), Yike Zhang(张一可), Tongzhou Ji(吉同舟), Rongxing Cao(曹荣幸), Bingfeng Miao(缪冰锋), Yonggang Zhao(赵永刚), and Haifeng Ding(丁海峰) Chin. Phys. B, 2024, 33 (3): 037501.   DOI: 10.1088/1674-1056/ad188f Abstract （223）   HTML （4）    PDF （1824KB）（233）       Knowledge map    Recent theory and experiments show that artificial magnetic skyrmions can be stabilized at room temperature without the need for the external magnetic field, casting strong potentials for the device applications. In this work, we study the electric field manipulation of artificial magnetic skyrmions imprinted by Co disks on CoPt multilayers utilizing the micromagnetic simulations. We find that the reversible annihilation and creation of skyrmions can be realized with the electric field via the strain mediated magnetoelastic coupling. In addition, we also demonstrate controllable manipulation of individual skyrmion, which opens a new platform for constructing magnetic field-free and low-energy dissipation skyrmion based media.

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