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Emergent topological states via digital(001.oxide superlattices

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npj Computational Materials 2022年第1期8卷 2015-2026页

作者： Zhiwei Liu Hongquan Liu Jiaji Ma Xiaoxuan wang Gang Li Hanghui Chen Key Laboratory of Polar Materials and Devices Ministry of EducationEast China Normal University200241ShanghaiChina nYU-ECnU Institute of physics NYU Shanghai200122ShanghaiChina Department of electronic Science East China Normal University200241ShanghaiChina school of Physical Science and Technology ShanghaiTech University201210ShanghaiChina ShanghaiTech Laboratory for Topological physics ShanghaiTech University201210ShanghaiChina Department of physics New York UniversityNew YorkNY10012USA

Oxide heterostructures exhibit many intriguing *** we provide design principles for inducing multiple topological states in(001.(AMO_(3))_(1./(AM′O_(3))_(1.oxide *** by first-principles calculations and model analysis,we show that a(SrMO_(3))_(1./(SrM′O_(3))_(1.superlattice(M=nb,Ta and M′=Rh,Ir)is a strong topological insulator with Z_(2)index(1.001..More remarkably,a(SrMoO_(3))1.(SrIrO_(3))_(1.superlattice exhibits multiple coexisting topological insulator(TI)and topological Dirac semi-metal(TDS)*** TDS state has a pair of type-II Dirac points near the Fermi level and symmetry-protected Dirac node *** surface TDS Dirac cone is sandwiched by two surface TI Dirac cones in the energy-momentum *** non-trivial topological properties arise from the band inversion between d orbitals of two dissimilar transition metal atoms and a particular parity property of(001.superlattice *** work demonstrates how to induce non-trivial topological states in(001.perovskite oxide heterostructures by rational design.

关键词： properties topological trivial

Theoretical insights into photochemical ESITP process for novel DMP-HBT-py compound

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Chinese physics B 2020年第10期29卷 222-226页

作者： Guang Yang Kaifeng Chen Gang wang Dapeng Yang Basic Teaching Department Jiaozuo UniversityJiaozuo 454000China Collaborative Innovation Center of Light Manipulations and Applications Shandong Normal UniversityJinan 250358China

We execute the density functional theory(DFT) and time-dependent density functional theory(TDDFT) approaches to make a detailed exploration about excited state luminescent properties as well as excited state intramolecular proton transfer(ESIPT) mechanism for the novel 2,6-dimethyl phenyl(DMP-HBT-py) system. Firstly, we check and confirm the formation and stabilization of hydrogen bonding interaction for DMP-HBT-py. Via optimized geometrical parameters of primary chemical bond and infrared(IR) spectra, we find O–H··· n hydrogen bond of DMP-HBT-py should be strengthened in S1.state. Insights into frontier molecular orbitals(MOs) analyses, we infer charge redistribution and charge transfer(ICT)phenomena motivate ESIPT trend. Via probing into potential energy curves(PECs) in related electronic states, we come up with the ultrafast ESIPT behavior due to low potential barrier. Furthermore, we search the reaction transition state(TS)structure, the ultrafast ESIPT behavior and mechanism of DMP-HBT-py compound can be re-confirmed. We sincerely wish this work could play roles in further developing novel applications based on DMP-HBT-py compound and in promoting efficient solid emitters in OLEDs in future.

关键词： infrared vibrational spectra intramolecular charge transfer potential energy curve excited state intramolecular proton transfer

Development characteristics of cloud-to-ground lightning with multiple grounding points

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Science china Earth Sciences 2018年第8期61卷 1127-1135页

作者： Bin FAn Ping YUAn Xuejuan wang Yang ZHAO Jianyong CEn Yanling SU Key Laboratory of Atomic and Molecular physics and Functional Materials of Gansu Province College of Physics and Electronic Engineering Northwest Normal University school of Atmospheric {1. Nanjing University of Information Science and Technology College of physics and Information {1. Shanxi Normal University

Using the optical images of a cloud-to-ground lightning flash with multiple grounding points obtained by a highspeed video system in the Qinghai Province of china along with synchronous radiated electric field information, the propagation characteristic and the electric field change features of the leaders and the grounding behavior of discharge channels are *** addition, the two-dimensional velocity of the leader was estimated and its correlation with the time interval of the corresponding subsequent return stroke, and that with the peak current of return stroke are investigated. The results show that the average distance between the three obvious grounded points of the first return stroke channel is about 51..7 m, and the average time interval between the pulses of the corresponding electric field fast changes is 3.8 μs. Further, the average time interval between electric field pulses from the stepped leader is smaller than that of {1. single grounding lightning. The observed lightning in our study has two main channels, namely the left and right channels. Based on our observations, it is clear that the dart leader comes close to the ground in case of the left channel after the first return stroke, but it fails to form a return ***, the right channel exhibits a relatively rare phenomenon in that the subsequent return stroke R2 occurred about 2.1.ms after the dart leader arrived at the ground, which was unusually long; this phenomenon might be attributed to the strong discharge of the first return stroke and insufficient charge accumulation near the grounded point in a timely manner. The two-dimensional velocities for the stepped leader of the two main channels are about 1.23×1.5 and 1.1.×1.5 m s-1. respectively. A sub-branch of stepped leader for the left channel fails to reach the ground and develops into an attempt leader eventually; this might be attributed to the fact that the main branch connects considerably many sub-branches, which lea

关键词： Multiple grounding lightning High-speed camera Electric field changes Leader

Spectral properties of Pr:CnGG crystals grown by micro-pulling-down method

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Chinese physics B 2019年第8期28卷 345-348页

作者： Yan-Yan Xue na Li Dong-Hua Hu Qing-Song Song Xiao-Dong Xu Dong-Hai wang Qing-Guo wang Dong-Zhen Li Zhan-Shan wang Jun Xu school of {1. Science and engineering Institute for Advanced StudyTongji UniversityShanghai 200092China Jiangsu Key Laboratory of Advanced Laser Materials and Devices School of Physics and Electronic EngineeringJiangsu Normal UniversityXuzhou 221116China

Pr^3+-doped calcium niobium gallium garnet(Pr:CnGG)single crystals with different Pr^3+concentrations are successfully grown by the micro-pulling-down(μ-PD)*** crystal structure,room-temperature absorption spectra,and fluorescence spectra of Pr:CnGG crystals are measured and *** fluorescence results indicate their large dependence on the doping *** fluorescence lifetime of the 1.2 energy level is also *** results indicate that Pr:CnGG crystal could be a potential solid-state laser gain medium.

关键词： Pr:CnGG μ-PD method spectral properties

Phase Selection and Microhardness of Directionally Solidified AlCoCrFeni_(2.1. Eutectic High-Entropy Alloy

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Acta Metallurgica Sinica(English Letters) 2022年第8期35卷 1281-1290页

作者： Peng Peng Shengyuan Li Weiqi Chen Yuanli Xu Xudong Zhang Zhikun Ma Jiatai wang school of Materials Science and Energy Lanzhou UniversityLanzhou 730000China Gansu Institute of Metrology Lanzhou 730071China school of {1. and electronic Information engineering Qinghai Normal UniversityXining 810000China

In the present work,the solidification behaviors and microhardness of directionally solidified AlCoCrFeni_(2.1. eutectic highentropy alloy(EHEA)obtained at different growth velocities are *** microstructure of the as-cast AlCoCrFeni_(2.1. EHEA is composed of bulky dendrites(niAl phase)and lamellar eutectic structures,indicating that the actual composition of the alloy slightly deviates from the eutectic ***,it is interesting to observe that the full lamellar structure of this alloy is obtained through directional *** order to explain this phenomenon,the maximum interface temperature criterion and the interface response function(IRF)theory are applied to calculate the velocity range of the transition from the primary phase to the eutectic,which is 1.2–2×1.^(4)μm/***,microhardness is one of the important parameters to measure the mechanical properties of ***,the microhardness test is performed,and the test result indicates that the microhardness(HV)increased with increasing growth velocity(V)or decreased with increasing lamellar spacing(λ).The dependences ofλand HV on V are determined by using a linear regression *** relationships between theλ,V and HV are given as:λ=1..62V^(-0.48),HV=305.5V 0.02 and HV=328.1.^(0.04),*** microhardness of the AlCoCrFeni_(2.1. EHEA increases from 31..38 HV to 329.54 HV with the increase in growth velocity(5–200μm/s).Thus,directional solidification is an effective method to improve the mechanical properties of alloys.

关键词： Directional solidification Eutectic high-entropy alloy Phase selection Microstructure Microhardness

Screening for new thermoelectric material: A semiconducting TaS_(3) with nanoporous structure

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Journal of Materiomics 2022年第5期8卷 1031-1037页

作者： Yangfan Cui Xiaojun wang Shuai Duan Xin Chen Xiaobing Liu Laboratory of High Pressure physics and Material Science(HPPMS) School of Physics and Physical EngineeringQufu Normal UniversityQufuShandong273165China Advanced Research Institute of Multidisciplinary Science Qufu Normal UniversityQufuShandong273165China

Transition-metal sulfides,such as 1.-and 2H-TaS_(2),are attracting considerable interest in modern condensed matter physics for their diverse behaviors of the Mott state,peculiar charge-density-wave phase and *** intrinsically low thermal conductivities along the cross-plane direction can advantage the potential high thermoelectric performance;yet,their insignificant power factors severely hampered the practical applications as thermoelectric *** this perspective,we herein present a new semiconducting phase in TaS_(3) with the space group C2/m predicted by the swarmintelligence structure-searching *** C2/m-TaS_(3) phase exhibits anisotropic multivalley band dispersions,which is beneficial for {1. ***,the unique structure within nanopores leads to strong anharmonic scattering,significantly reducing the lattice thermal *** a result,the calculated figure of merit ZT can reach up to 1.68 and 1.57 at 800 K for p-and n-type,respectively that is comparable with conventional thermoelectric materials(***,Bi_(2)Te_(3)).Therefore,our calculation reveals that the C2/m-TaS_(3) phase can be a potential high-performance candidate as nontoxic and eco-friendly thermoelectrics,and will stimulate further experimental exploration for understanding and tailoring thermoelectric capability in related transition-metal sulfides.

关键词： Transition-metal sulfides Thermoelectric performance First-principles calculations electronic structure Thermal conductivity

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电子信息类本科生科研能力和意愿的问卷分析

创新创业理论研究与实践 2024年第7期7卷 67-70,178页

作者：李竹王大为芦宾赵红梅山西师范大学物理与信息工程学院山西太原030031

为了进一步提高学生科研能力,该文针对1.4年级的所有电子信息类本科生进行了6种科学研究能力和2种科研意愿驱动的问卷调查。通过对问卷数据逐项分析,发现了科研能力的弱项和提高科研意愿的突破点;最后根据电子信息类本科生的共性特点和... 详细信息

为了进一步提高学生科研能力,该文针对1.4年级的所有电子信息类本科生进行了6种科学研究能力和2种科研意愿驱动的问卷调查。通过对问卷数据逐项分析,发现了科研能力的弱项和提高科研意愿的突破点;最后根据电子信息类本科生的共性特点和个性差异,落实SRT(大学生科研训练)计划,给出了嵌入式、三级制和导师制3种科研能力训练的建议。

关键词：能力意愿梯度嵌入式三级制导师制

Transport in electron–photon systems

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Frontiers of physics 2023年第4期18卷 129-175页

作者： Jian-Sheng wang Jiebin Peng Zu-Quan Zhang Yong-Mei Zhang Tao Zhu Department of physics National University of SingaporeSingapore 117551Republic of Singapore Center for Phononics and Thermal Energy Science China-EU Joint Center for NanophononicsShanghai Key Laboratory of Special Artificial Microstructure Materials and TechnologySchool of Physics Science and EngineeringTongji UniversityShanghai 200092China Department of physics Zhejiang Normal UniversityJinhua 321004China College of physics Nanjing University of Aeronautics and AstronauticsNanjing 210016China school of {1. and Information engineering Tiangong UniversityTianjin 300387China Beijing national Laboratory for Condensed Matter physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China

We review the description and modeling of transport phenomena among the electron systems coupled via scalar or vector *** consists of three *** first part is about scalar photons,i.e.,Coulomb *** second part is with transverse photons described by vector *** third part is onϕ=0 or temporal gauge,which is a full theory of the *** use the nonequilibrium Green’s function(nEGF)formalism as a basic tool to study steady-state *** with local equilibrium it is equivalent to the fluctuational electrodynamics(FE),the advantage of nEGF is that it can go beyond FE due to its *** have given a few examples in the review,such as transfer of heat between graphene sheets driven by potential bias,emission of light by a double quantum dot,and emission of energy,momentum,and angular momentum from a graphene *** of these calculations are based on a generalization of the Meir–Wingreen formula commonly used in electronic transport in mesoscopic systems,with materials properties represented by photon self-energy,coupled with the Keldysh equation and the solution to the Dyson equation.

关键词： quantum transport thermal radiation scalar and vector photons nonequilibrium Green's function

Crystal and electronic structure {1. of tin monoxide by external pressure

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Journal of Advanced Ceramics 2021年第3期10卷 565-577页

作者： Kun LI Junjie wang Vladislav ABLATOV Yutong GOnG naotoUMEZAWA Tomofumi TADA Hideo HOSOnO Artem ROGAnOV State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China International Center for Materials Discovery School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Samara Center for Theoretical Materials Science(SCTMS) Samara State Technical UniversitySamara 443100Russia Samara Center for Theoretical Materials Science(SCTMS) Samara UniversitySamara 443011Russia Semiconductor R&D Center Samsung ElectronicsGyeonggi-do 18448Republic of Korea Materials Research Center for Element Strategy Tokyo Institute of TechnologyKanagawa 226-8503Japan Skolkovo Institute of Science and Technology Moscow 143026Russia Moscow Institute of physics and Technology Dolgoprudny 141700Russia

Although tin monoxide (SnO) is an interesting compound due to its p-type conductivity,a widespread application of SnO has been limited by its narrow band gap of 0.7 *** this work,we theoretically investigate the structural and electronic properties of several SnO phases under high pressures through employing van der Waals (vdW) *** calculations reveal that a metastable SnO (β-SnO),which possesses space group P2_(1./c and a wide band gap of 1.9 eV,is more stable than α-SnO at pressures higher than 80 ***,a stable (space group P2/c) and a metastable (space group Pnma) phases of SnO appear at pressures higher than 1.0 *** and topological analyses show that P2/c-SnO has a high possibility to directly transform to β-SnO at around 1.0 *** work also reveals that β-SnO is a necessary intermediate state between high-pressure phase Pnma-SnO and low-pressure phase α-SnO for the phase transition path Pnma-SnO →β-SnO →α-*** phase transition analyses indicate that there is a high possibility to synthesize β-SnO under high-pressure conditions and have it remain stable under {1. ***,our study reveals that the conductive property of β-SnO can be engineered in a low-pressure range (0-9 GPa)through a semiconductor-to-metal transition,while maintaining transparency in the visible light range.

关键词： tin monoxide van der Waals(vdW) topological relationship phase transition band gap