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Magnetic topological insulator MnBi6Te10 with a zero-field ferromagnetic state and gapped Dirac surface states

Physical Review B 2020年第3期102卷 035144-035144页

作者： Shangjie Tian (田尚杰) Shunye Gao (高顺业) Simin Nie (聂思敏) Yuting Qian (钱玉婷) Chunsheng Gong (龚春生) Yang Fu (付阳) Hang Li (李航) Wenhui Fan (樊文辉) Peng Zhang (张鹏) Takesh Kondo Shik Shin Johan Adell Hanna Fedderwitz Hong Ding (丁洪) Zhijun Wang (王志俊) Tian Qian (钱天) Hechang Lei (雷和畅) Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices Renmin University of China Beijing 100872 China Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences Beijing 100190 China University of Chinese Academy of Sciences Beijing 100049 China Department of Materials Science and Engineering Stanford University Stanford California 94305 USA Institute for Solid State Physics University of Tokyo Kashiwa Chiba 277-8581 Japan AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory (OPERANDO-OIL) Kashiwa Chiba 277-8581 Japan MAX IV Laboratory Lund University P.O. Box 118 221 00 Lund Sweden Songshan Lake Materials Laboratory Dongguan Guangdong 523808 China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing 100049 China

Magnetic topological insulators (TIs) with nontrivial topological electronic structure and broken time-reversal symmetry exhibit various exotic topological quantum phenomena. The realization of such exotic phenomena at high temperature is one of the central topics in this area. We reveal that MnBi6Te10 is a magnetic TI with an antiferromagnetic ground state below 10.8 K whose nontrivial topology is manifested by Dirac-like surface states. The ferromagnetic axion insulator state with Z4=2 emerges once spins are polarized at a field as low as 0.1 T, accompanied with saturated anomalous Hall resistivity up to 10 K. Such a ferromagnetic state is preserved even with an external field down to zero at 2 K. Theoretical calculations indicate that the few-layer ferromagnetic MnBi6Te10 is also topologically nontrivial with a nonzero Chern number. Angle-resolved photoemission spectroscopy experiments further reveal three types of Dirac surface states arising from different terminations on the cleavage surfaces, one of which has insulating behavior with an energy gap of ∼28 meV at the Dirac point. These outstanding features suggest that MnBi6Te10 is a promising system to realize various topological quantum effects at zero field and high temperature.

关键词： Antiferromagnets Chern insulators Electronic structure Ferromagnets Single crystal materials Topological insulators Angle-resolved photoemission spectroscopy Crystal growth First-principles calculations Magnetization measurements Resistivity measurements

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Magnetic-Field Control of Topological Electronic Response near Room Temperature in Correlated Kagome Magnets

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Physical Review Letters 2019年第19期123卷 196604-196604页

作者： Yangmu Li Qi Wang Lisa DeBeer-Schmitt Zurab Guguchia Ryan D. Desautels Jia-Xin Yin Qianheng Du Weijun Ren Xinguo Zhao Zhidong Zhang Igor A. Zaliznyak Cedomir Petrovic Weiguo Yin M. Zahid Hasan Hechang Lei John M. Tranquada Condensed Matter Physics and Materials Science Division Brookhaven National Laboratory Upton New York 11973 USA Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices Renmin University of China Beijing 100872 China Neutron Scattering Division Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA Laboratory for Topological Quantum Matter and Advanced Spectroscopy Department of Physics Princeton University Princeton New Jersey 08544 USA Laboratory for Muon Spin Spectroscopy Paul Scherrer Institute CH-5232 Villigen PSI Switzerland Materials Science and Chemical Engineering Department Stony Brook University Stony Brook New York 11790 USA Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley California 94720 USA

Strongly correlated kagome magnets are promising candidates for achieving controllable topological devices owing to the rich interplay between inherent Dirac fermions and correlation-driven magnetism. Here we report tunable local magnetism and its intriguing control of topological electronic response near room temperature in the kagome magnet Fe3Sn2 using small angle neutron scattering, muon spin rotation, and magnetoresistivity measurement techniques. The average bulk spin direction and magnetic domain texture can be tuned effectively by small magnetic fields. Magnetoresistivity, in response, exhibits a measurable degree of anisotropic weak localization behavior, which allows the direct control of Dirac fermions with strong electron correlations. Our work points to a novel platform for manipulating emergent phenomena in strongly correlated topological materials relevant to future applications.

关键词： Dirac fermions Electrical properties Magnetism Kagome lattice Strongly correlated systems Small angle neutron scattering

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Phonon anomalies and magnetic excitations in BaFe2Se2O

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Physical Review B 2019年第14期99卷 144419-144419页

作者： Feng Jin Nenad Lazarević Changle Liu Jianting Ji Yimeng Wang Shuna He Hechang Lei Cedomir Petrovic Rong Yu Zoran V. Popović Qingming Zhang Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices Renmin University of China Beijing 100872 China Center for Solid State Physics and New Materials Institute of Physics Belgrade University of Belgrade Pregrevica 118 11080 Belgrade Serbia State Key Laboratory of Surface Physics and Department of Physics Fudan University Shanghai 200433 China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China Condensed Matter Physics and Materials Science Department Brookhaven National Laboratory Upton New York 11973-5000 USA Serbian Academy of Sciences and Arts Knez Mihailova 35 Belgrade 11000 Serbia School of Physical Science and Technology Lanzhou University Lanzhou 730000 China

We report a temperature- and magnetic-field-dependent Raman-scattering study of the spin-ladder compound BaFe2Se2O. Temperature evolution of the B1g mode self-energies revealed anomalous behavior at about 100 and 240 K with strong temperature-dependent Fano asymmetry. Furthermore, the Ag modes integrated intensity exhibits an additional change in tendency at about 50 K. All the observed anomalies can be traced back to spin-phonon interaction contributions as well as multiple magnetic phase transitions present in BaFe2Se2O also detected in the Raman continuum induced by the spin fluctuations. Moreover, the absence of magnetic-field dependence of the magnetic mode observed at 436cm−1 and the small linewidth and high intensity are different from the magnetic modes at about 650cm−1. This suggests a two-magnon continuum and a two-magnon bound state resonance for this mode.

关键词： Lattice dynamics Magnetic phase transitions Optical phonons

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Giant pressure-enhancement of multiferroicity in CuBr2

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Physical Review Research 2020年第1期2卷 013144-013144页

作者： J. S. Zhang Yiqi Xie X. Q. Liu A. Razpopov V. Borisov C. Wang J. P. Sun Y. Cui J. C. Wang X. Ren Hongshan Deng Xia Yin Yang Ding Yuan Li J. G. Cheng Ji Feng R. Valentí B. Normand Weiqiang Yu Mathematics and Physics Department North China Electric Power University Beijing 102206 China Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices Renmin University of China Beijing 100872 China International Center for Quantum Materials School of Physics Peking University Beijing 100871 China Institut für Theoretische Physik Goethe-Universität Frankfurt 60438 Frankfurt am Main Germany Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences Beijing 100190 China School of Physical Sciences University of Chinese Academy of Sciences Beijing 100190 China Center for High Pressure Science and Technology Advanced Research (HPSTAR) Beijing 100193 China Collaborative Innovation Center of Quantum Matter Beijing 100871 China Songshan Lake Materials Laboratory Dongguan Guangdong 523808 China Neutrons and Muons Research Division Paul Scherrer Institute CH-5232 Villigen-PSI Switzerland

Type-II multiferroic materials, in which ferroelectric polarization is induced by inversion nonsymmetric magnetic order, promise new and highly efficient multifunctional applications based on the mutual control of magnetic and electric properties. Although this phenomenon has to date been limited to low temperatures, here we report a giant pressure dependence of the multiferroic critical temperature in CuBr2. At 4.5 GPa, TC is enhanced from 73.5 to 162 K, to our knowledge the highest value yet reported for a nonoxide type-II multiferroic. This growth shows no sign of saturating and the dielectric loss remains small under these high pressures. We establish the structure under pressure and demonstrate a 60% increase in the two-magnon Raman energy scale up to 3.6 GPa. First-principles structural and magnetic energy calculations provide a quantitative explanation in terms of dramatically pressure-enhanced interactions between CuBr2 chains. These large, pressure-tuned magnetic interactions motivate structural control in cuprous halides as a route to applied high-temperature multiferroicity.

关键词： Capacitance Dielectric properties Pressure effects Multiferroics First-principles calculations Neutron scattering Nuclear magnetic resonance Raman spectroscopy X-ray diffraction

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Diatoms silica: An emerging biomaterial for energy conversion and storage

Diatoms silica: An emerging biomaterial for energy conversio...

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第二届中国（国际）能源材料化学研讨会

作者： Tian Wang Qiujian Le Yuxin Zhang Dusan Losic College of Materials Science and Engineering Chongqing University National Key Laboratory of Fundamental Science of Micro/Nano-Devices and SystemTechnology Chongqing University School of Chemical Engineering The University of Adelaide

We would like to introduce diatom as a novel substrate of electrode material for supercapacitor,which is actually the amorphous silica exoskeletons(frustules)of the single-celled algae and known as a common building *... 详细信息

关键词： An emerging biomaterial for energy conversion and storage Diatoms silica

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A topologically substituted boron nitride hybrid aerogel for highly selective CO2 uptake

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nano Research 2018年第12期11卷 6325-6335页

作者： R.Govindan Kutty Sivaramapanicker Sreejith Xianghua Kong Haiyong He Hong Wang Junhao Lin Kazu Suenaga Chwee Teck Lim Yanli Zhao Wei Ji Zheng Liu Center for Programmable Materials School of Materials Sdence and EngineeringNanyang Technological UniversitySO Nanyang Avenue639798Singapore School of Materials Science and EngineeringNanyang Technological UniversitySingapore 639798Singapore Center for Advanced 2D Materials and Graphene Research Center National University of Singapore6Science Drive 2Singapore117546Singapore Biomedical Institute for Global Health Research and Technology National University of Singapore14Medical DriveSingapore 117599Singapore Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-Nano Devices Renmin University of ChinaBeijing 100872China National Institute of Advanced Industrial Science and Technology (AIST) AIST Central 5Tsukuba305-8565-Japan Division of Chemistry and Biological Chemistry School of Physical and Mathematical SciencesNanyang Technological University21-Nanyang LinkSingapore 637371Singapore Department of Biomedical Engineering National University of SingaporeSingapore 117543Singapore

A topologically mediated synthesis of porous boron nitride aerogel has been experimentally and theoretically investigated for carbon dioxide (CO2) uptake. Replacement of the carbon atoms in a precursor aerogel of grap... 详细信息

A topologically mediated synthesis of porous boron nitride aerogel has been experimentally and theoretically investigated for carbon dioxide (CO₂) uptake. Replacement of the carbon atoms in a precursor aerogel of graphene oxide and carbon nanotubes was achieved using an elemental substitution reaction, to obtain a boron and nitrogen framework. The newly prepared BN aerogel possessed a specific surface area of 716.56 m²/g and exhibited an unprecedented twentyfold increase in CO₂ uptake over N₂, adsorbing 100 cc/g at 273 K and 80 cc/g in ambient conditions, as verified by adsorption isotherms via the multipoint Brunauer-Emmett-Teller (BET) method. Density functional theory calculations were performed to give hints on the mechanism of such high selectivity of CO₂ over N₂ adsorption in BN aerogel, which may be due to the interaction between the intrinsic polar nature of B-N bonds and the high quadrupole moment of CO₂ over N₂.

关键词： boron nitride boron nitride nanotube aerogel quadrupole moment selective CO2 adsorption

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Deriving phosphorus atomic chains from few-layer black phosphorus

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nano Research 2017年第7期10卷 2519-2526页

作者： Zhangru Xiao Jingsi Qiao Wanglin Lu Guojun Ye Xianhui Chen Ze Zhang Wei Ji Jixue Li Chuanhong Jin State Key Laboratory of Silicon Materials School of Materials Science and Engineering Zhejiang University Hangzhou 310027 China Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices Renmin University ot China Beijing 100872 China Key Laboratory of Strongly-coupled Quantum Matter Physics Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics University of Science and Technology of China Hefei 230026 China Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing 210093 China

Phosphorus atomic chains, the narrowest nanostructures of black phosphorus （BP）, are highly relevant to the in-depth development of BP-based one-dimensional （1D） nano-electronics components. In this study, we report a top-down route for the preparation of phosphorus atomic chains via electron beam sculpturing inside a transmission electron microscope （TEM）. The growth and dynamics （i.e., rupture and edge migration） of 1D phosphorus chains are experimentally captured for the first time. Furthermore, the dynamic behavior and associated energetics of the as-formed phosphorus chains are further investigated by density functional theory （DFT） calculations. It is hoped that these 1D BP structures will serve as a novel platform and inspire further exploration of the versatile properties of BP.

关键词： black phosphorus one-dimensionalatomic chain density functional theory

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Thick SU8 microstructures prepared by broadband UV lithography and the applications in MEMS devices

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Optoelectronics Letters 2016年第3期12卷 182-187页

作者：李东玲温志渝尚正国佘引 National Key Laboratory of Fundamental Science of Novel Micro/Nano Device and System Technology Key Laboratory of Optoelectronic Technology and System of the Education Ministry of China Micro System Reaserch CenterChongqing University

Thick SU8 microstructures with high aspect ratio and good side wall quality were fabricated by ultraviolet （UV） lithography, and the processing parameters were comprehensively studied. It proves that the adhesion of SU8 on silicon （Si） substrates is influenced by Si-OH on the surface, and can be improved by the HF treatment. Cracks and de- lamination are caused by large internal stress during fabrication process, and are significantly influenced by soft bake and post-exposure bake processes. The internal stress is reduced by a low post-exposure bake exposure tem- perature of 85 ℃ for 40 rain. A three-step soft bake enhances the reflowing ofSU8 photoresist, and results in uni- form surface and less air bubbles. The vertical side wall is obtained with the optimized exposure dose of 800 mJ/cm2 for the thickness of 160 μm. Using the optimized fabrication process combined with a proper structure design, dense SU8 micro pillars are achieved with the aspect ratio of 10 and the taper angle of 89.86°. Finally, some possible ap- plications of SU8 in micro-electromechanical system （MEMS） device are developed and demonstrated.

关键词： MEMS器件紫外光刻微结构应用微机电系统烘烤过程编写宽带

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Rare-earth chalcogenides: A large family of triangular lattice spin liquid candidates

arXiv

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arXiv 2018年

作者： Liu, Weiwei Zhang, Zheng Ji, Jianting Liu, Yixuan Li, Jianshu Wang, Xiaoqun Lei, Hechang Chen, Gang Zhang, Qingming National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing100190 China Department of Physics Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices Renmin University of China Beijing100872 China Department of Physics and Astronomy Shanghai Jiao Tong University Shanghai200240 China State Key Laboratory of Surface Physics Department of Physics Fudan University Shanghai200433 China School of Physical Science and Technology Lanzhou University Lanzhou730000 China

Frustrated quantum magnets are expected to host many exotic quantum spin states like quantum spin liquid (QSL), and have attracted numerous interest in modern condensed matter physics. The discovery of the triangular lattice spin liquid candidate YbMgGaO4 stimulated an increasing attention on the rare-earth-based frustrated magnets with strong spin-orbit coupling. Here we report the synthesis and characterization of a large family of rare-earth chalcogenides AReCh2 (A = alkali or monovalent ions, Re = rare earth, Ch = O, S, Se). The family compounds share the same structure (R¯3m) as YbMgGaO4, and antiferromagnetically coupled rare-earth ions form perfect triangular layers that are well separated along the c-axis. Specific heat and magnetic susceptibility measurements on NaYbO2, NaYbS2 and NaYbSe2 single crystals and polycrystals, reveal no structural or magnetic transition down to 50mK. The family, having the simplest structure and chemical formula among the known QSL candidates, removes the issue on possible exchange disorders in YbMgGaO4. More excitingly, the rich diversity of the family members allows tunable charge gaps, variable exchange coupling, and many other advantages. This makes the family an ideal platform for fundamental research of QSLs and its promising applications. Copyright © 2018, The Authors. All rights reserved.

关键词： Gallium compounds

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Photonic microwave true time delays for phased array antennas using a 49 GHz FSR integrated optical micro-comb source[Invited]

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Photonics Research 2018年第5期6卷 I0055-I0061页

作者： XINGYUAN Xu JIAYANG Wu THACH G.NGUYEN TANIA MOEIN SAI T.CHU BRENT E.LITTLE ROBERTO MORANDOTTI ARNAN MITCHELL DAVID J.Moss Centre for Micro-Photonics Swinburne University of TechnologyHawthornVlC 3122Australia ARC Centre of Excellence for Ultrahigh-bandwidth Devices for Optical Systems(CUDOS) RMIT UniversityMelbourneVIC 3001Australia Department of Physics and Material Science City University of Hong KongTat Chee AvenueHong KongChina State Key Laboratory of Transient Optics and Photonics Xi'an Institute of Optics and Precision MechanicsChinese Academy of SciencesXi'an 710119China INRS-Energie Materiaux et Telecommunications1650 Boulevard Lionel-BouletVarennesQuebec J3X 1S2Canada National Research University of Information Technologies Mechanics and OpticsSt.PetersburgRussia Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of ChinaChengdu 610054China

We demonstrate significantly improved performance of a microwave true time delay line based on an integrated optical frequency comb source. The broadband micro-comb(over 100 nm wide) features a record low free spectral range(FSR) of 49 GHz, resulting in an unprecedented record high channel number(81 over the C band)—the highest number of channels for an integrated comb source used for microwave signal processing. We theoretically analyze the performance of a phased array antenna and show that this large channel count results in a high angular resolution and wide beam-steering tunable range. This demonstrates the feasibility of our approach as a competitive solution toward implementing integrated photonic true time delays in radar and communications systems.

关键词： Photonic microwave true time delays for phased array antennas a 49 GHz FSR integrated optical micro-comb source

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