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Tunable quantum anomalous Hall effects in ferromagnetic van der Waals heterostructures

National Science Review 2024年第3期11卷 100-107页

作者： Feng Xue Yusheng Hou Zhe Wang Zhiming Xu ke he Ruqian Wu Yong Xu Wenhui Duan Beijing Academy of Quantum Information Sciences State key Laboratory of Low Dimensional Quantum Physics Department of Physics Tsinghua University Guangdong Provincial key Laboratory of Magnetoelectric Physics and Devices Center for Neutron Science and Technology School of Physics Sun Yat-sen University State key Laboratory of Surface Physics Key Laboratory of Computational Physical Sciences and Department of PhysicsFudan University Frontier Science Center for Quantum Information Department of Physics and Astronomy University of California-Irvine Tencent Quantum Laboratory Tencent Technology(Shenzhen)Co.Ltd RIkeN Center for Emergent Matter Science(CEMS) Institute for Advanced Study Tsinghua University

The quantum anomalous Hall effect（QAhe） has unique advantages in topotronic applications, but it is still challenging to realize the QAhe with tunable magnetic and topological properties for building functional devices. Through systematic first-principles calculations, we predict that the in-plane magnetization induced QAhe with Chern numbers C = ±1 and the out-of-plane magnetization induced QAhe with high Chern numbers C = ±3 can be realized in a single material candidate, which is composed of van der Waals（vdW）coupled Bi and MnBi2Te4monolayers. The switching between different phases of QAhe can be controlled in multiple ways, such as applying strain or（weak） magnetic field or twisting the vdW materials. The prediction of an experimentally available material system hosting robust, highly tunable QAhe will stimulate great research interest in the field. Our work opens a new avenue for the realization of tunable QAhe and provides a practical material platform for the development of topological electronics.

关键词： quantum anomalous Hall effect topological quantum phase transition van der Waals heterostructures tunable Chern number high Chern number

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Effect of heat Treatment on Gradient Microstructure and Tensile Property of Laser Powder Bed Fusion Fabricated 15-5 Precipitation Hardening Stainless Steel

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Acta Metallurgica Sinica(English Letters) 2024年第1期37卷 181-195页

作者： Sheng Cao Hongyu Liu Jin Jiang ke he Binghua Lv Hao Zhang Lujie Zhang Jingrong Meng Hao Deng Xiaodong Niu Department of Mechanical Engineering College of EngineeringShantou UniversityShantou515063China China State Shipbuilding Co. Ltd.Huangpu Wenchong Shipbuilding Company Ltd.Guangzhou510715China Faculty of Materials and Manufacturing Beijing University of TechnologyBeijing100080China Shantou Ruixiang Mould Co. Ltd.Shantou515041China Military Representative Office X of Unit 93147 Deyang618000China China National Erzhong Group Co. Deyang Wanhang Die Forging Co.Ltd.Deyang618013China

This work investigated the gradient microstructure evolution and tensile property of LPBF fabricated 15-5 precipitation hardening stainless steel in post-process direct ageing(DA)and solution treating&ageing(STA).The varied microstructures for austenite and small-sized oxide inclusions at different sample heights in the as-built(AB)condition was generally preserved after DA ***,austenite was almost disappeared,and oxide particle grew significantly after the STA *** a result,the tensile property differences in sample top and bottom for AB and DA conditions did not occur in the STA *** the influence of post-process heat treatment,the STA condition had the highest yield strength due to the highest volume fraction of nano-sized Cu ***,the DA specimen had the highest ultimate tensile strength and elongation owing to the considerable amount of austenite phase and associated transformation induced plasticity effect.

关键词： 15-5 PH stainless steel Laser powder bed fusion heat treatment Gradient microstructures Tensile properties

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Assessing the range of blasting-induced cracks in the surrounding rock of deeply buried tunnels based on the unified strength theory

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Journal of Central South University 2024年第7期31卷 2341-2364页

作者： LI Liang CheN Jia-jun ZHAO Lian-heng he ke-pei HU Shi-hong LI Hua-long School of Civil Engineering Central South UniversityChangsha 410075China key Laboratory of heavy-haul Railway Engineering Structure Ministry of EducationCentral South UniversityChangsha 410075China Hunan Provincial key Laboratory for Disaster Prevention and Mitigation of Rail Transit Engineering Structure Central South UniversityChangsha 410075China

Blasting-induced cracks in the rock surrounding deeply buried tunnels can result in water gushing and rock mass collapse,posing significant safety ***,previous theoretical studies on the range of blasting-induced cracks often ignore the impact of the in-situ stress,especially that of the intermediate principal *** particle displacement−crack radius relationship was established in this paper by utilizing the blasthole cavity expansion equation,and theoretical analytical formulas of the stress−displacement relationship and the crack radius were derived with unified strength theory to accurately assess the range of cracks in deep surrounding rock under a blasting *** analysis showed that the crushing zone size was positively correlated with in-situ stress,intermediate principal stress,and detonation pressure,whereas negatively correlated with Poisson ratio and decoupling *** dilatancy angle-crushing zone size relationship exhibited nonmonotonic *** relationships in the crushing zone and the fracture zone exhibited opposite trends under the influence of only in-situ stress or intermediate principal *** the in-situ stress increased from 0 to 70 MPa,the rate of change in the crack range and the attenuation rate of the peak vibration velocity gradually slowed.

关键词： deep drilling and blasting cracks in surrounding rock unified strength theory intermediate principle stress in-situ stress cavity expansion dilatancy characteristics

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View of thermodynamic phase transition of the charged Gauss-Bonnet AdS black hole via the shadow

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Chinese Physics B 2024年第4期33卷 355-362页

作者：何柯腱郭森罗智李国平 College of Physics Chongqing UniversityChongqing 401331China Guangxi key Laboratory for Relativistic Astrophysics School of Physical Science and TechnologyGuangxi UniversityNanning 530004China School of Physics and Astronomy China West Normal UniversityNanchong 637000China

We examine thermodynamic phase transition(PT)of the charged Gauss-Bonnet Ad S black hole(BH)by utilizing the shadow *** this system,we rescale the corresponding Gauss-Bonnet coefficientαby a factor of 1/(D-4),and ensure thatαis positive to avoid any singularity *** equation derived for the shadow radius indicates that it increases as the event horizon radius increases,making it an independent variable for determining BH *** investigating the PT curve in relation to shadows,we can observe that the shadow radius can be used as an alternative to the event horizon radius in explaining the phenomenon of BH ***,the results indicate that an increase in the parameterαcorresponds to a decrease in the temperature of the *** utilizing the relationship between the temperature and the shadow radius,it is possible to obtain the thermal profile of the Gauss-Bonnet AdS *** is evident that there is an N-type variation in temperature for pressures Phe parameterαincreases,the region covered by shadow expands while the temperature *** utilization of BH shadows as a probe holds immense significance in gaining a deeper understanding of BH thermodynamic behavior.

关键词： Gauss-Bonnet AdS black hole thermodynamic shadow

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Observational appearance and extra photon rings of an asymmetric thin-shell wormhole with a Bardeen profile

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Chinese Physics C 2024年第6期48卷 211-221页

作者：何柯腱罗智郭森李国平 Department of Physics Chongqing UniversityChongqing 401331China Guangxi key Laboratory for Relativistic Astrophysics School of Physical Science and TechnologyGuangxi UniversityNanning 530004China School of Physics and Astronomy China West Normal UniversityNanchong 637000China

In this work,the optical appearance of an asymmetric thin-shell wormhole with a Bardeen profile is *** initiate the process,we need to construct an asymmetric thin-shell wormhole utilizing the cut-and-paste technique proposed by Visser and subsequently ascertain its pertinent physical quantities such as the radius of the photon sphere and critical impact parameters for different values of magnetic charge ***,the effective potential and motion behavior of photons are also investigated within the framework of asymmetric thin-shell wormholes with a Bardeen *** can be found that the effective potential,ray trajectory,and azimuthal angle of the thin-shell wormhole exhibit a strong correlation with the mass ratio of black *** considering the accretion disk as the sole background light source,we observe additional photon rings and lensing bands in the optical appearance of the asymmetric thin-shell wormhole with a Bardeen profile compared to those exhibited by the Bardeen black *** can find that there is an increase in the size of the specific additional light bands with increasing magnetic charge g,which is different from the black hole *** exceptionally luminous rings can serve as a robust criterion for the identification and characterization of the thin-shell wormhole spacetime.

关键词： shadow asymmetric thin-shell wormhole Bardeen black hole

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Triple points and phase transitions of D-dimensional dyonic Ad S black holes with quasitopological electromagnetism in Einstein–Gauss–Bonnet gravity

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Chinese Physics B 2024年第6期33卷 272-287页

作者：牟平辉蒋青权何柯腱李国平 School of Physics and Astronomy China West Normal UniversityNanchong 637000China College of Physics Chongqing UniversityChongqing 401331China

By considering the negative cosmological constant Λ as a thermodynamic pressure, we study the thermodynamics and phase transitions of the D-dimensional dyonic Ad S black holes(BHs) with quasitopological electromagnetism in Einstein–Gauss–Bonnet(EGB) gravity. The results indicate that the small/large BH phase transition that is similar to the van der Waals(vdW) liquid/gas phase transition always exists for any spacetime dimensions. Interestingly, we then find that this BH system exhibits a more complex phase structure in 6-dimensional case that is missed in other ***, it shows for D = 6 that we observed the small/intermediate/large BH phase transitions in a specific parameter region with the triple point naturally appeared. Moreover, when the magnetic charge turned off, we still observed the small/intermediate/large BH phase transitions and triple point only in 6-dimensional spacetime, which is consistent with the previous results. However, for the dyonic Ad S BHs with quasitopological electromagnetism in Einstein–Born–Infeld(EBI) gravity, the novel phase structure composed of two separate coexistence curves observed by Li et al. [Phys. Rev. D105 104048(2022)] disappeared in EGB gravity. This implies that this novel phase structure is closely related to gravity theories, and seems to have nothing to do with the effect of quasitopological electromagnetism. In addition, it is also true that the critical exponents calculated near the critical points possess identical values as mean field theory. Finally, we conclude that these findings shall provide some deep insights into the intriguing thermodynamic properties of the dyonic Ad S BHs with quasitopological electromagnetism in EGB gravity.

关键词： AdS black hole phase transition triple point

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Investigation of helicity-dependent photocurrent of surface states in(Bi_(0.7)Sb_(0.3))_(2)Te_(3)nanoplate

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Chinese Physics B 2024年第5期33卷 573-578页

作者：喻钦俞金玲陈涌海赖云锋程树英何珂 School of Advanced Manufacturing Fuzhou UniversityQuanzhou 362251China Institute of Micro/Nano Devices and Solar Cells School of Physics and Information EngineeringFuzhou UniversityFuzhou 350108China key Laboratory of Semiconductor Materials Science Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering Changzhou UniversityChangzhou 213164China Department of Physics State Key Laboratory of Low Dimensional Quantum PhysicsTsinghua UniversityBeijing 100084China

helicity-dependent photocurrent(HDPC)of the surface states in a high-quality topological insulator(Bi_(0.7)Sb_(0.3))_(2)Te_(3)nanoplate grown by chemical vapor deposition(CVD)is *** investigating the angle-dependent HDPC,it is found that the HDPC is mainly contributed by the circular photogalvanic effect(CPGE)current when the incident plane is perpendicular to the connection of the two contacts,whereas the circular photon drag effect(CPDE)dominates the HDPC when the incident plane is parallel to the connection of the two *** addition,the CPGE of the(Bi_(0.7)Sb_(0.3))_(2)Te_(3)nanoplate is regulated by temperature,light power,excitation wavelength,the source–drain and ionic liquid top-gate voltages,and the regulation mechanisms are *** is demonstrated that(Bi_(0.7)Sb_(0.3))_(2)Te_(3)nanoplates may provide a good platform for novel opto-spintronics devices.

关键词： (Bi_(0.7)Sb_(0.3))_(2)Te_(3)nanoplate helicity-dependent photocurrent circular photogalvanic effect ionic liquid gating

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基于多特征深度子空间聚类的高光谱影像波段选择

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遥感学报 2024年第1期28卷 132-141页

作者：何珂孙伟伟黄可陈镔捷杨刚宁波大学地理与空间信息技术系宁波315211

高光谱影像受到高维波段间强相关性的困扰,导致处理应用的困难。而现有高光谱波段选择方法通常以线性角度考虑波段间关系,未充分考虑多尺度的信息且容易受到噪声的影响,导致所选的波段子集性能不佳。为了克服上述问题,本文提出了基于多... 详细信息

高光谱影像受到高维波段间强相关性的困扰,导致处理应用的困难。而现有高光谱波段选择方法通常以线性角度考虑波段间关系,未充分考虑多尺度的信息且容易受到噪声的影响,导致所选的波段子集性能不佳。为了克服上述问题,本文提出了基于多特征的深度子空间聚类方法进行高光谱影像波段选择。该方法将自表达层嵌入到卷积自编码器中学习子空间自表达系数,充分考虑了空间信息和光谱信息的交互,用非线性的视角思考了波段间关系。为了提高潜在表征的学习能力,提升自表达系数学习的准确性,本文将注意力模块和多特征提取模块与卷积自编码器相结合,进一步降低了异常值的干扰。本文在3个高光谱遥感影像数据集上,将提出的方法与几种经典主流的方法进行多种对比实验,证明了本文方法能够选择具有代表性的波段子集。

关键词：高光谱遥感降维波段选择多特征深度子空间聚类

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Quantized anomalous Hall resistivity achieved in molecular beam epitaxy-grown Mn Bi2Te4 thin films

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National Science Review 2024年第2期11卷 24-32页

作者： Yunhe Bai Yuanzhao Li Jianli Luan Ruixuan Liu Wenyu Song Yang Chen Peng-Fei Ji Qinghua Zhang Fanqi Meng Bingbing Tong Lin Li Yuying Jiang Zongwei Gao Lin Gu Jinsong Zhang Yayu Wang Qi-Kun Xue ke he Yang Feng Xiao Feng State key Laboratory of Low Dimensional Quantum Physics Department of Physics Tsinghua University Institute of Physics Chinese Academy of Sciences School of Materials Science and Engineering Tsinghua University Beijing Academy of Quantum Information Sciences Frontier Science Center for Quantum Information hefei National Laboratory Southern University of Science and Technology

The intrinsic magnetic topological insulator MnBi2Te4provides a feasible pathway to the high-temperature quantum anomalous Hall（QAH） effect as well as various novel topological quantum phases. Although quantized transport properties have been observed in exfoliated MnBi2Te4thin flakes, it remains a big challenge to achieve molecular beam epitaxy（MBE）-grown MnBi2Te4thin films even close to the quantized regime. In this work, we report the realization of quantized anomalous Hall resistivity in MBE-grown MnBi2Te4thin films with the chemical potential tuned by both controlled in situ oxygen exposure and top gating. We find that elongated post-annealing obviously elevates the temperature to achieve quantization of the Hall resistivity, but also increases the residual longitudinal resistivity, indicating a picture of high-quality QAH puddles weakly coupled by tunnel barriers. These results help to clarify the puzzles in previous experimental studies on MnBi2Te4and to find a way out of the big difficulty in obtaining MnBi2Te4samples showing quantized transport properties.

关键词： intrinsic magnetic topological insulator quantized anomalous Hall resistivity molecular beam epitaxy quantized transport property

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视网膜中央动脉阻塞的治疗进展

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国际眼科杂志 2024年第3期24卷 411-414页

作者：何珂张鹏西北大学附属医院·西安市第三医院中国陕西省西安市710018

视网膜中央动脉(CRA)是视网膜神经上皮层内五层组织的血供来源。若CRA发生阻塞,可导致患眼视力骤降甚至永久性视力丧失。视网膜中央动脉阻塞(CRAO)患者的自然视力预后通常较差。虽然可用于CRAO治疗的手段多样,如眼球按摩、前房穿刺术、... 详细信息

视网膜中央动脉(CRA)是视网膜神经上皮层内五层组织的血供来源。若CRA发生阻塞,可导致患眼视力骤降甚至永久性视力丧失。视网膜中央动脉阻塞(CRAO)患者的自然视力预后通常较差。虽然可用于CRAO治疗的手段多样,如眼球按摩、前房穿刺术、高压氧治疗(HBOT)以及组织型纤溶酶原激活剂(tPA)动脉内溶栓等,但尚未有基于循证医学证据的CRAO治疗指南被应用于临床。而这些治疗手段对于CRAO的疗效均存在争议或存在治疗风险。本文将对目前可应用于CRAO治疗的措施予以综述,并对其各自的安全性及有效性进行探讨。

关键词：视网膜栓塞治疗动脉进展

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