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Tunable quantum anomalous Hall effects in ferromagnetic van der Waals heterostructures

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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

Radiation build-up and dissipation in Raman random fiber laser

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science China(information sciences) 2024年第1期67卷 254-260页

作者： Shengtao LIN Zinan WANG Jiaojiao ZHANG Pan WANG Han WU Yifei QI key laboratory of Optical Fiber Sensing and Communications University of Electronic Science and Technology of China College of Electronics and information Engineering Sichuan University

Raman random fiber laser(RRFL) is a complex physical system that arises from the distributed Raman amplification and the intrinsic stochasticity of fiber *** analysis of the underlying lightwave kinetics at steady state has been the focus of considerable ***,the transient state,such as the RRFL build-up and dissipation,is particularly important for revealing the lightwave interaction ***,we investigate for the first time the RRFL dynamics at the transient state and track the RRFL temporal and spectral evolution theoretically and ***,with the contribution of random distributed feedback,RRFL build-up exhibits continuous Verhulst logistic growth curves without cavity-related features,which is significantly different from the step-like growth curve of conventional fiber ***,the radiation build-up duration is inversely related to the pump power,and the spectral evolution of the RRFL undergoes two phases,i.e.,from spectral density increase to spectral *** the steady state to the pump switch-off state,the RRFL output power dissipates immediately,and the remaining Stokes lightwave from the Rayleigh scattering will gradually disappear after one round *** work provides new insights into the transient dynamic features of the RRFL.

关键词： random fiber laser stimulated Raman scattering transient phenomenon nonlinear optics łinebreak biological growth dynamics

Decarboxylative cyanation and thiocyanation via catalytic electron donor-acceptor complex with copper catalysis

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science China Chemistry 2024年第9期67卷 3019-3028页

作者： Hongping Zhao Xiaoxiang Xi Tianbao Wu Zimin Chen Minyan Wang Weiming Yuan key laboratory of Material Chemistry for Energy Conversion and Storage Ministry of EducationHubei Key Laboratory of Bioinorganic Chemistry and Materia MedicaSchool of Chemistry and Chemical EngineeringHuazhong University of Science and Technology(HUST)Wuhan 430074China State key laboratory of Coordination Chemistry School of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210093China shenzhen Huazhong University of science and technology Research Institute Shenzhen 518000China

A new catalytic decarboxylative cyanation and thiocyanation via a synergistic Na I/Cu catalysis is *** photoexcited electron donor-acceptor complex by assembly of Na I,R3P,and N-acyloxy-phthalimide ester(NHPI ester)triggers the generation of alkyl radical species,which then engages in Cu-catalyzed radical coupling *** to success of this dual catalytic transformation is the reliable charge transfer between I·and Cu(I).This dual catalytic platform can eliminate the use of expensive iridium-based photocatalyst or synthetically elaborate organic dyes.A series of primary,secondary,and tertiary alkyl nitriles and thiocyanates are easily ***,an asymmetric decarboxylative cyanation by applying a chiral Cu catalyst is also developed to afford chiral nitriles in high *** mechanistic details and the origin of the high enantioselectivity are further investigated by the mechanistic experiments and the density functional theory calculations.

关键词： electron donor-acceptor catalysis copper catalysis cyanation thiocyanation asymmetric synthesis

Coupling Co-Ni phosphides for energy-saving alkaline seawater splitting

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Nano Research 2024年第6期17卷 4797-4806页

作者： Weijia Liu Wenxian Liu Tong Hou Junyang Ding Zhigui Wang Ruilian Yin Xingyuan San Ligang Feng Jun Luo Xijun Liu State key laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures Guangxi Key Laboratory of Processing for Nonferrous Metals and Featured MaterialsMOE Key Laboratory of New Processing Technology for Nonferrous Metals and MaterialsSchool of ResourcesEnvironment and MaterialsGuangxi UniversityNanning 530004China College of Materials science and Engineering Zhejiang University of TechnologyHangzhou 310014China Hebei key laboratory of Optic-electronic information and Materials the College of Physics Science and TechnologyHebei UniversityBaoding 071002China School of Chemistry and Chemical Engineering Yangzhou UniversityYangzhou 225002China ShenSi Lab Shenzhen Institute for Advanced StudyUniversity of Electronic Science and Technology of ChinaShenzhen 518110China

The coupling of energy-saving small molecule conversion reactions and hydrogen evolution reaction(HER)in seawater electrolytes can reduce the energy consumption of seawater electrolysis and mitigate chlorine corrosion ***,the fabrication of efficient multifunctional catalysts for this promising technology is of great ***,a heterostructured catalyst comprising CoP and Ni_(2)P on nickel foam(CoP/Ni_(2)P@NF)is reported for hydrazine oxidation(HzOR)-assisted alkaline seawater *** coupling of CoP and Ni_(2)P optimizes the electronic structure of the active sites and endows excellent electrocatalytic performance for HzOR and ***,the two-electrode HzOR-assisted alkaline seawater splitting(OHzS)cell based on the CoP/Ni_(2)P@NF required only 0.108 V to deliver 100 mA·cm^(−2),much lower than 1.695 V for alkaline seawater electrolysis ***,the OHzS cell exhibits satisfactory stability over 48 h at a high current density of 500 mA·cm^(−2).Furthermore,the CoP/Ni_(2)P@NF heterostructured catalyst also efficiently catalyzed glucose oxidation,methanol oxidation,and urea oxidation in alkaline seawater *** work paves a path for high-performance heterostructured catalyst preparation for energy-saving seawater electrolysis for H_(2) production.

关键词： seawater splitting heterostructure electrocatalysis hydrazine oxidation reaction hydrogen evolution reaction

Addressable structured light system using metasurface optics and an individually addressable VCSEL array

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Photonics Research 2024年第6期12卷 1129-1137页

作者： CHENYANG WU XUANLUN HUANG YIPENG JI TINGYU CHENG JIAXING WANG NAN CHI SHAOHUA YU CONNIE J.CHANG-HASNAIN School of information science and technology Fudan UniversityShanghai 200433China Berxel Photonics Co. Ltd.Shenzhen 518071China Peng Cheng laboratory Shenzhen 518055China Chinese University of Hong Kong Shenzhen 518172China

Structured-light(SL)based 3D sensors have been widely used in many *** SL is the most widely deployed among all SL sensors due to its light weight,compact size,fast video rate,and low *** transmitter(known as the dot projector)consists of a randomly patterned vertical-cavity surface-emitting laser(VCSEL)array multiplicated by a diffractive optical element(DOE)with a fixed repeated *** that the separation of any two speckles is only one known and fixed number(albeit random),there are no other known scales to cal-ibrate or ***,typical SL sensors require extensive in-factory calibrations,and the depth resolution is limited to 1 mm at-60 cm *** this paper,to the best of our knowledge,we propose a novel dot projector and a new addressable SL(ASL)3D sensor by using a regularly spaced,individually addressable VCSEL array,multiplicated by a metasurface-DOE(MDOE)into a random pattern of the *** turning on or off the VCSELs in the array provides multiple known distances between neighboring speckles,which is used as a“built-in caliper”to achieve higher accuracy of *** as a precise“vernier caliper,”the addressable VCSEL array enables fine control over speckle positions and high detection *** experimentally dem-onstrated that the proposed method can result in sub-hundred-micron level *** new concept opens new possibilities for applications such as 3D computation,facial recognition,and wearable devices.

关键词： speckle light surface

A CSP-based retraining framework for motor imagery based brain-computer interfaces

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science China(information sciences) 2024年第8期67卷 349-350页

作者： Xue JIANG Lubin MENG Xinru CHEN Dongrui WU key laboratory of Image Processing and Intelligent Control School of Artificial Intelligence and AutomationHuazhong University of Science and Technology shenzhen Huazhong University of science and technology Research Institute

Motor imagery(MI) is a classic paradigm of electroencephalogram(EEG)-based brain-computer interfaces(BCIs). It entails individuals mentally imagining the movement of a body part without physically performing it. EEG s... 详细信息

关键词： Classification (of information)

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Interfacial Electronic Modulation of Dual-Monodispersed Pt–Ni_(3)S_(2) as Efficacious Bi-Functional Electrocatalysts for Concurrent H_(2) Evolution and Methanol Selective Oxidation

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Nano-Micro Letters 2024年第4期16卷 415-431页

作者： Qianqian Zhao Bin Zhao Xin Long Renfei Feng Mohsen Shakouri Alisa Paterson Qunfeng Xiao Yu Zhang Xian‑Zhu Fu Jing‑Li Luo shenzhen key laboratory of Energy Electrocatalytic Materials Shenzhen Key Laboratory of Polymer Science and TechnologyGuangdong Research Center for Interfacial Engineering of Functional MaterialsCollege of Materials Science and EngineeringShenzhen UniversityShenzhen 518060People’s Republic of China Canadian Light Source Inc. SaskatoonSK S7N 0X4Canada Instrumental Analysis Center of shenzhen University(Lihu Campus) Shenzhen UniversityShenzhen 518055People’s Republic of China

Constructing the efficacious and applicable bifunctional electrocatalysts and establishing out the mechanisms of organic electro-oxidation by replacing anodic oxygen evolution reaction(OER) are critical to the development of electrochemicallydriven technologies for efficient hydrogen production and avoid CO_(2) emission. Herein, the hetero-nanocrystals between monodispersed Pt(~ 2 nm) and Ni_(3)S_(2)(~ 9.6 nm) are constructed as active electrocatalysts through interfacial electronic modulation, which exhibit superior bi-functional activities for methanol selective oxidation and H_(2) generation. The experimental and theoretical studies reveal that the asymmetrical charge distribution at Pt–Ni_(3)S_(2) could be modulated by the electronic interaction at the interface of dual-monodispersed heterojunctions, which thus promote the adsorption/desorption of the chemical intermediates at the interface. As a result, the selective conversion from CH_(3)OH to formate is accomplished at very low potentials(1.45 V) to attain 100 m A cm^(-2) with high electronic utilization rate(~ 98%) and without CO_(2) emission. Meanwhile, the Pt–Ni_(3)S_(2) can simultaneously exhibit a broad potential window with outstanding stability and large current densities for hydrogen evolution reaction(HER) at the cathode. Further, the excellent bi-functional performance is also indicated in the coupled methanol oxidation reaction(MOR)//HER reactor by only requiring a cell voltage of 1.60 V to achieve a current density of 50 m A cm^(-2) with good reusability.

关键词： Dual-monodispersed heterostructure Electronic interactive modulation Reaction mechanism Methanol oxidation reaction Hydrogen generation

Linear shallow neural network to accelerate transmitter dispersion eye closure quaternary(TDECQ) assessment

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science China(information sciences) 2024年第4期67卷 337-338页

作者： Junjiang XIANG Zejun CHEN Yijun CHENG Hailin YANG Xuancheng HUO Meng XIANG Gai ZHOU Yuwen QIN Songnian FU Institute of Advanced Photonics technology School of Information EngineeringGuangdong University of Technology School of Optical and Electronic information Huazhong University of Science and Technology key laboratory of Photonic technology for Integrated Sensing and Communication Ministry of Education of ChinaGuangdong University of Technology Guangdong Provincial key laboratory of information Photonics technology Guangdong University of Technology

To support the ever-emerging capacity requirement of datacenter interconnection(DCI) applications, transmitter dispersion eye closure quaternary(TDECQ) has been proposed by IEEE802.3 standard [1], which is specifically employed for the four-level pulse amplitude modulation(PAM-4) signals. However, the traditional scheme of TDECQ assessment needs several iterative operations,

关键词： IEEE Standards

Enhancing thermoelectric performance in P-type Mg_(3)Sb_(2)-based Zintls through optimization of band gap structure and nanostructuring

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Journal of Materials science & technology 2024年第3期170卷 25-32页

作者： Yi-bo Zhang Ji-Sheng Liang Chengyan Liu Qi Zhou Zhe Xu Hong-bo Chen Fu-cong Li Ying Peng Lei Miao Guangxi key laboratory of information Material Engineering Research Center of Electronic Information Materials and DevicesMinistry of EducationSchool of Material Science and EngineeringGuilin University of Electronic TechnologyGuilin 541004China Guangxi key laboratory for Relativity Astrophysics Center on Nanoenergy ResearchGuangxi Key Laboratory of Processing for Nonferrous Metal and Featured MaterialsSchool of Physical Science&TechnologyGuangxi UniversityNanning 530004China Guangxi key laboratory of Precision Navigation technology and Application Guilin University of Electronic TechnologySchool of Information and CommunicationGuilin 541004China

P-type Mg_(3)Sb_(2)-based Zintls have attracted considerable interest in the thermoelectric(TE)field due to their environmental friendliness and low ***,compared to their n-type counterparts,they show relatively low TE performance,limiting their application in TE *** this work,we simultaneously introduce Bi alloying at Sb sites and Ag doping at Mg sites into the Mg_(3)Sb_(2)to coopera-tively optimize the electrical and thermal properties for the first time,acquiring the highest ZT value of∼0.85 at 723 K and a high average ZT of 0.39 in the temperature range of 323-723 K in sample Mg_(2.94)Ag_(0.06)Sb_(1.9)Bi_(0.1).The first-principle calculations show that the codoping of Ag and Bi can shift the Fermi level into the valence band and narrow the band gap,resulting in the increased carrier concentration from 3.50×10^(17)cm^(-3)in the reference Mg 3 Sb 0.9 Bi 0.1 to∼7.88×10^(19)cm^(-3)in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi *** a result,a remarkable power factor of∼778.9μW m^(-1)K^(-2)at 723 K is achieved in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi ***,a low lattice thermal conductivity of∼0.48 W m^(-1)K^(-1)at 723 K is also obtained with the help of phonon scattering at the distorted lattice,point defects,and nano-precipitates in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi *** synergistic effect of using the multi-element co-doping/-alloying to optimize electrical properties in Mg_(3)Sb_(2)holds promise for further improving the TE performance of Zintl phase materials or even others.

关键词： Thermoelectric materials Band engineering Nanostructuring P-type Mg_(3)Sb_(2) Ag and Bi Co-doping