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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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A polarized^(3)He system based on metastability-exchange optical pumping

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Science China(physics,Mechanics & Astronomy) 2024年第7期67卷 72-81页

作者： Yuting Wang Liangyong Wu Kaiyuan Zhang Mei Peng Siyu Chen Haiyang Yan State key laboratory of Nuclear physics and Technology School of PhysicsPeking UniversityBeijing 100871China Institute of Nuclear physics and Chemistry China Academy of Engineering PhysicsMianyang 621900China key laboratory of Nuclear physics and Ion-beam Application(MOE) Fudan UniversityShanghai 200433China key laboratory of neutron physics Institute of Nuclear Physics and ChemistryChina Academy of Engineering PhysicsMianyang 621900China

Hyperpolarized^(3)He nuclei have emerged as a significantly important approach in quantum precision measurement techniques,with extensive applications in fundamental physics,magnetometry,metrology,and beyond.In this study,we report on the design and implementation of a^(3)He polarization system at the China Mianyang Research Reactor(CMRR),utilizing the metastabilityexchange optical pumping(MEOP)method.We employed a Merritt coil system consisting of four square coils to furnish a uniform holding field.We deployed a 2 W fiber laser to pump the metastable^(3)He atoms and conducted free induction decay(FID)detection of the polarized^(3)He nuclei using both pickup coil and optical methods.For the optical method,we used a50 m W linearly polarized distributed Bragg reflector(DBR)laser as the probe.We applied transverse light absorption polarimetry to measure the absolute nuclear polarization of the ground-state^(3)He.We have developed cell fabrication capabilities at the CMRR,and cells at various pressures ranging from 100 to 1000 Pa have been fabricated and evaluated.For a typical borosilicate cell with 100 Pa pressure,the absolute polarization is measured as Pn≈70%,and the transverse relaxation time is estimated as T2≈0.5 s.Moreover,we constructed a few aluminosilicate cells,each carefully filled with pure^(3)He at a pressure of 100 Pa.Subsequently,we conducted a comprehensive evaluation of their performance in the context of MEOP.

关键词： metastability exchange optical pumping polarized^(3)He magnetic resonance

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Angular and planar transport properties of antiferromagnetic V5S8

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Chinese physics B 2024年第2期33卷 83-88页

作者：吴晓凯王彬吴德桐陈博文弭孟娟王以林沈冰 Center for neutron Science and Technology and School of physics Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devicesand Key Laboratory of Optoelectronic Materials and Technologies Sun Yat-Sen University School of Integrated Circuits Shandong Technology Center of Nanodevices and Integration State Key Laboratory of Crystal MaterialsShandong University

Systemically angular and planar transport investigations are performed in layered antiferromagnetic(AF) V5S8. In this AF system, obvious anomalous Hall effect(AHE) is observed with a large Hall angle of 0.1 compared to that in ferromagnetic(FM) system. It can persist to the temperatures above AF transition and exhibit strong angular field dependence.The phase diagram reveals various magnetic states by rotating the applied field. By analyzing the anisotropic transport behavior, magnon contributions are revealed and exhibit obvious angular dependence with a spin-flop vanishing line. The observed prominent planar Hall effect and anisotropic magnetoresisitivity exhibit two-fold systematical angular dependent oscillations. These behaviors are attributed to the scattering from spin–orbital coupling instead of nontrivial topological origin. Our results reveal anisotropic interactions of magnetism and electron in V5S8, suggesting potential opportunities for the AF spintronic sensor and devices.

关键词： antiferromagnetism magnetic and topological properties planar Hall effect

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Micelle-directed self-assembly of single-crystal-like mesoporous stoichiometric oxides for high-performance lithium storage

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National Science Review 2024年第4期11卷 195-205页

作者： Yanhua Wan Changyao Wang Xingmiao Zhang Yang Yin Mengmeng Liu Bing Ma Linlin Duan Yuzhu Ma Wei Zhang Changlin Zheng Dongliang Chao Fei Wang Yongyao Xia Wei Li Department of Chemistry Laboratory of Advanced Materials Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials State Key Laboratory of Molecular Engineering of Polymers College of Chemistry and Materials ScienceFudan University State key laboratory of Surface physics and Department of physics Fudan University

Due to their uncontrollable assembly and crystallization process,the synthesis of mesoporous metal oxide single crystals remains a formidable challenge.Herein,we report the synthesis of single-crystal-like mesoporous Li2TiSiO5by using soft micelles as templates.The key lies in the atomic-scale self-assembly and step-crystallization processes,which ensure the formation of single-crystal-like mesoporous Li2TiSiO5microparticles via an oriented attachment growth mechanism under the confinement of an in-situ formed carbon matrix.The mesoporous Li2TiSiO5anode achieves a superior rate capability(148 mAh g-1at5.0 A g-1) and outstanding long-term cycling stability(138 mAh g-1after 3000 cycles at 2.0 A g-1) for lithium storage as a result of the ultrafast Li+diffusion caused by penetrating mesochannels and nanosized crystal frameworks（5-10 nm）.In comparison,bulk Li2TiSiO5exhibits poor rate capability and cycle performance due to micron-scale diffusion lengths.This method is very simple and reproducible,heralding a new way of designing and synthesizing mesoporous single crystals with controllable frameworks and chemical functionalities.

关键词： mesoporous materials micelles single-crystal-like Li2TiSiO5 lithium-ion batteries

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Design and implementation of the monochromator shielding for the cold neutron spectrometers XINGZHI and BOYA

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Chinese physics B 2024年第5期33卷 96-102页

作者：汪晋辰刘娟娟徐大业 Florian Grünauer 郝丽杰刘蕴韬张红霞程鹏鲍威 laboratory for neutron Scattering and Beijing key laboratory of Optoelectronic Functional Materials and MicroNano Devices Department of PhysicsRenmin University of ChinaBeijing 100872China physics Consulting Zorneding 85604Germany China Institute of Atomic Energy Beijing 102413China Department of physics City University of Hong KongKowloon 999077China Center for neutron Scattering City University of Hong KongKowloon 999077China

An innovative monochromator shielding is designed and implemented for the cold neutron spectrometers XINGZHI and BOYA operated by Renmin University of China at China Advanced Research Reactor.Via Monte Carlo simulations and careful mechanical designs,a shielding configuration has been successfully developed to satisfy safety requirements of below 3μSv/h dose rate at its exterior,meanwhile fulfilling space,floor load and nonmagnetic requirements.Composite materials are utilized to form the sandwich-type shielding walls:the inner layer of boron carbide rubber,the middle layer of steel-encased lead and the outer layer of borated polyethylene.Special-shaped liftable shielding blocks are incorporated to facilitate a continuous adjustment of the neutron energy while preventing radiation leakage.Our work has demonstrated that by utilizing composite shielding materials,along with the sandwich structure and liftable shielding blocks,a compact and lightweight shielding solution can be achieved.This enables the realization of advanced neutron scattering instruments that provide expanded space of measurement,larger energy and momentum coverage,and higher flux on the sample.This shielding represents the first of its kind in neutron scattering instruments in China.Following its successful operation,it has been subsequently employed by other neutron instruments across the country.

关键词： neutron scattering cold neutron spectrometer monochromator shielding sandwich shielding structure

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Recent advances in protein conformation sampling by combining machine learning with molecular simulation

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Chinese physics B 2024年第3期33卷 80-87页

作者：唐一鸣杨中元姚逸飞周运谈圆王子超潘瞳熊瑞孙俊力韦广红 Department of physics State Key Laboratory of Surface Physicsand Key Laboratory for Computational Physical Sciences (Ministry of Education)Shanghai 200438China

The rapid advancement and broad application of machine learning(ML)have driven a groundbreaking revolution in computational biology.One of the most cutting-edge and important applications of ML is its integration with molecular simulations to improve the sampling efficiency of the vast conformational space of large biomolecules.This review focuses on recent studies that utilize ML-based techniques in the exploration of protein conformational landscape.We first highlight the recent development of ML-aided enhanced sampling methods,including heuristic algorithms and neural networks that are designed to refine the selection of reaction coordinates for the construction of bias potential,or facilitate the exploration of the unsampled region of the energy landscape.Further,we review the development of autoencoder based methods that combine molecular simulations and deep learning to expand the search for protein conformations.Lastly,we discuss the cutting-edge methodologies for the one-shot generation of protein conformations with precise Boltzmann weights.Collectively,this review demonstrates the promising potential of machine learning in revolutionizing our insight into the complex conformational ensembles of proteins.

关键词： machine learning molecular simulation protein conformational space enhanced sampling

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Boron-doped high-entropy oxide toward high-rate and long-cycle layered cathodes for wide-temperature sodium-ion batteries

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Journal of Energy Chemistry 2024年第8期95卷 577-587页

作者： Yuzhen Dang Zhe Xu Yurong Wu Runguo Zheng Zhiyuan Wang Xiaopin Lin Yanguo Liu Zheng-Yao Li Kai Sun Dongfeng Chen Dan Wang School of Materials Science and Engineering Northeastern University School of Resources and Materials Northeastern University at Qinhuangdao key laboratory of Dielectric and Electrolyte Functional Material Hebei Province neutron Scattering laboratory Department of Nuclear Physics China Institute of Atomic Energy

03-type layered metal oxides hold great promise for sodium-ion batteries cathodes owing to their energy density advantage.However,the severe irreversible phase transition and sluggish Na+diffusion kinetics pose significant challenges to achieve high-performance layered cathodes.Herein,a boron-doped03-type high entropy oxide Na(Fe0.2Co0.15Cu0.05Ni0.2Mn0.2Ti0.2)B0.02O2(NFCCNMT-B0.02) is designed and the covalent B-O bonds with high entropy configuration ensure a robust layered structure.The obtained cathode NFCCNMT-B0.02exhibits impressive cycling performance（capacity retention of 95% and 82% after100 cycles and 300 cycles at 1 and 10 C,respectively） and outstanding rate capability(capacity of 83 mAh g-1at 10 C).Furthermore,the NFCCNMT-B0.02demonstrates a superior wide-temperature performance,maintaining the same capacity level(113,4 mAh g-1@-20℃,121 mAh g-1@25℃,and 119 mAh g-1@60℃) and superior cycle stability（90% capacity retention after 100 cycles at 1 C at-20℃）.The high-entropy configuration design with boron doping strategy contributes to the excellent sodium-ion storage performance.The high-entropy configuration design effectively suppresses irreversible phase transitions accompanied by small volume changes（ΔV=0.65 ?3）.B ions doping expands the Na layer distance and enlarges the P3 phase region,thereby enhancing Na+diffusion kinetics.This work offers valuable insights into design of high-performance layered cathodes for sodium-ion batteries operating across a wide temperature.

关键词： Born substitution High entropy oxide Na+ diffusion kinetics Phase transition Sodium-ion batteries

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Recent progress of in-situ characterization of LiNi_(1−x−y)Co_(x)Mn_(y)O_(2) cathodes for lithium metal batteries: A mini review

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Nano Research 2024年第3期17卷 1384-1401页

作者： Huanzhu Lv Xiaoqi Zhu Jun Mei Yuanhua Xia Bin Wang Institute of Fundamental and Frontier Science University of Electronic Science and Technology of ChinaChengdu 611731China Chengdu Development Center of Science and Technology China Academy of Engineering PhysicsChengdu 610200China key laboratory of neutron physics and Institute of Nuclear physics and Chemistry China Academy of Engineering Physics(CAEP)Mianyang 621999China

In the context of the gradual popularity of electric vehicles(EVs),the development of lithium battery systems with high energy density and power density is regarded as the foremost way to improve the range of EVs.LiNi_(1-x-y)Co_(x)Mn_(y)O_(2)(NCM)cathodes have been the focus of researchers due to their high energy density,excellent power performance,and low-temperature resistance.However,the elaboration of the decay mechanism of NCM cathode based on lithium metal batteries(LMBs)is still being restricted to the primary level.In the past decades,the development and application of advanced in-situ characterization tools have facilitated researchers'understanding of the internal operation mechanism of batteries during charging and discharging.In this minireview,the latest progress of in-situ observation of the NCM cathode by X-ray diffraction(XRD),fourier transform infrared(FT-IR)spectroscopy,Raman spectroscopy,atomic force microscopy(AFM),transmission electron microscope(TEM),optical microscope,and other characterization tools is summarized.The mechanisms of structural degradation,cathode-electrolyte interfaces(CEIs)composition,and dynamic changes of NCM,electrolyte breakdown,and gas production are elaborated.Finally,based on the existing research progress,the opportunities and challenges for future in-situ characterization technology in the study of the mechanism of LMBs are discussed in depth.Therefore,the purpose of this minireview is to summarize recent work that focuses on the outstanding application of in-situ characterization techniques in the mechanistic study of LMBs,and pointing the way to the future development of high energy density and power density LMBs systems.

关键词： lithium metal batteries(LMBs) In-situ characterization LiNi_(1-x-y)Co_(x)Mn_(y)O_(2)(NCM)

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C-Type Antiferromagnetic Structure of Topological Semimetal CaMnSb2

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Chinese physics Letters 2024年第3期41卷 119-125页

作者：李博曾旭涛徐千惠杨帆项俊森钟恒扬邓司浩何伦华徐菊萍殷雯鲁兴业刘慧颖胜献雷金文涛 School of physics Beihang University Beijing National laboratory for Condensed Matter physics and Institute of PhysicsChinese Academy of Sciences Center for Advanced Quantum Studies and Department of physics Beijing Normal University Spallation neutron Source Science Center 5. Songshan Lake Materials laboratory

Determination of the magnetic structure and confirmation of the presence or absence of inversion (P) and time reversal (Τ) symmetry is imperative for correctly understanding the topological magnetic materials. Here h... 详细信息

关键词： Density functional theory

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High-performance,low-power,and flexible ultraviolet photodetector based on crossed ZnO microwires p-n homojunction

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Photonics Research 2024年第4期12卷 648-662页

作者： SHULIN SHA KAI TANG MAOSHENG LIU PENG WAN CHENYANG ZHU DANING SHI CAIXIA KAN MINGMING JIANG College of physics MIIT Key Laboratory of Aerospace Information Materials and PhysicsKey Laboratory for Intelligent Nano Materials and DevicesNanjing University of Aeronautics and AstronauticsNanjing 211106China

Low-power, flexible, and integrated photodetectors have attracted increasing attention due to their potential applications of photosensing, astronomy, communications, wearable electronics, etc. Herein, the samples of ZnO microwires having p-type(Sb-doped ZnO, ZnO:Sb) and n-type(Ga-doped ZnO, ZnO:Ga) conduction properties were synthesized individually. Sequentially, a p-n homojunction vertical structure photodiode involving a single ZnO:Sb microwire crossed with a ZnO:Ga microwire, which can detect ultraviolet light signals, was constructed.

关键词： power ultraviolet conduction

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