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Electronic origin of the unusual thermal properties of copper-based semiconductors:The s-d coupling-induced large phonon anharmonicity

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Science China(Physics,Mechanics & Astronomy) 2023年第7期66卷 112-119页

作者： Kaike Yang huai Yang Yujia sun Zhongming wei Jun Zhang Ping-Heng Tan Jun-wei Luo Shu-Shen Li su-huai wei Hui-Xiong Deng State Key Laboratory of superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Key Laboratory for Matter Microstructure and Function of Hunan ProvinceSynergetic Innovation Center for Quantum Effects and ApplicationsDepartment of PhysicsHunan Normal UniversityChangsha 410081China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Beijing Computational Science Research Center Beijing 100193China

Copper(Cu)-based materials(such as cuprates,Cu chalcogenides,and Cu halides)often exhibit unusual properties such as superconductivity,ultralow thermal conductivity,and ***,the electronic origin of these unusual behaviors remains *** this study,we demonstrate that the high-lying occupied 3d orbital of Cu causes a strong s-d coupling with its unoccupied 4s state when local symmetry is *** leads to strong phonon anharmonicity and is responsible for these intriguing *** example,during thermal transport,symmetry-controlled s-d coupling can substantially lower the lattice potential barrier,thereby enhancing the anharmonicity and scattering between phonons and ultimately significantly reducing lattice thermal *** confirmed this understanding with Raman spectra measurements,which demonstrated a remarkable red shift in the phonon vibrational frequency with an increase in the temperature of Cu-based *** study shows that the cause of phonon anharmonicity is related to the fundamental electronic structures,which can also explain other unusual physical properties of the Cu compounds.

关键词： anharmonicity copper-based semiconductor electronic structure thermal conductivity

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Graph deep learning accelerated efficient crystal structure search and feature extraction

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npj Computational Materials 2023年第1期9卷 524-532页

作者： Chuan-Nan Li Han-Pu Liang Xie Zhang Zijing Lin su-huai wei Department of Physics University of Science and Technology of ChinaHefei 230026China Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China Beijing Computational Science Research Center Beijing 100193China School of Materials Science and Engineering Northwestern Polytechnical UniversityXi’an 710072China

Structural search and feature extraction are a central subject in modern materials design,the efficiency of which is currently limited,but can be potentially boosted by machine learning(ML).Here,we develop an ML-based prediction-analysis framework,which includes a symmetry-based combinatorial crystal optimization program(SCCOP)and a feature additive attribution model,to significantly reduce computational costs and to extract property-related structural *** method is highly accurate and predictive,and extracts structural features from desired structures to guide materials *** first test SCCOP on 35 typical compounds to demonstrate its *** a case study,we apply our approach to a two-dimensional B-C-N system,which identifies 28 previously undiscovered stable structures out of 82 compositions;our analysis further establishes the structural features that contribute most to energy and *** to conventional approaches,SCCOP is about 10 times faster while maintaining a comparable *** framework is generally applicable to all types of systems for precise and efficient structural search,providing insights into the relationship between ML-extracted structural features and physical properties.

关键词： structural crystal precise

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Theoretical understanding of correlation between magnetic phase transition and the superconducting dome in high-Tc cuprates

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Science China(Physics,Mechanics & Astronomy) 2024年第2期67卷 167-173页

作者： Chen Zhang Cai-Xin Zhang su-huai wei Haiqing Lin Hui-Xiong Deng State Key Laboratory of superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Beijing Computational Science Research Center Beijing 100193China

Many issues concerning the origin of high-temperature superconductivity(HTS)are still under *** example,how the magnetic order varies with doping and its relationship with the superconducting temperature(Tc);and why Tcalways peaks near the quantum critical *** this paper,taking hole-doped La_(2)CuO_(4)as a classical example,we employ the first-principles band structure and total energy calculations with Monte Carlo simulations to explore how the symmetry-breaking magnetic ground state evolves with hole doping and the origin of a dome-shaped superconductivity region in the phase *** demonstrate that the local antiferromagnetic order and doping play key roles in determining the electron-phonon coupling,thus ***,the La_(2)CuO_(4)possesses a checkerboard local antiferromagnetic ground *** the hole doping increases,Tcincreases with the enhanced electron-phonon coupling *** as the doping increases further,the strength of the antiferromagnetic interaction weakens and spin fluctuation *** the critical doping level,a magnetic phase transition occurs that reduces the local antiferromagnetism-assisted electron-phonon coupling,thus diminishing the *** superconductivity disappears in the heavily overdoped region when the ferromagnetic order *** observations could account for why cuprates have a dome-shaped superconductivity region in the phase *** study,thus,contributes to a fundamental understanding of the correlation between doping,local magnetic order,and superconductivity of HTS.

关键词： high-temperature superconductivity antiferromagnetic order electron-phonon coupling doping effect cuprates

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Group velocity matters for accurate prediction of phonon-limited carrier mobility

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Chinese Physics B 2021年第8期30卷 449-455页

作者： Qiao-Lin Yang Hui-Xiong Deng su-huai wei aJun-wei Luo State Key Laboratory of superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Beijing Computational Science Research Center Beijing 100193China Beijing Academy of Quantum Information Sciences Beijing 100193China

First-principles approaches have recently been developed to replace the phenomenological modeling approaches with adjustable parameters for calculating carrier mobilities in ***,in addition to the high computational cost,it is still a challenge to obtain accurate mobility for carriers with a complex band structure,e.g.,hole mobility in common ***,we present a computationally efficient approach using isotropic and parabolic bands to approximate the anisotropy valence bands for evaluating group velocities in the first-principles *** treatment greatly reduces the computational cost in two ways:relieves the requirement of an extremely denseκmesh to obtain a smooth change in group velocity,and reduces the 5-dimensional integral to 3-dimensional *** Si and SiC as two examples,we find that this simplified approach reproduces the full first-principles calculation for *** we use experimental effective masses to evaluate the group velocity,we can obtain hole mobility in excellent agreement with experimental data over a wide temperature *** findings shed light on how to improve the first-principles calculations towards predictive carrier mobility in high accuracy.

关键词： electron-phonon interaction phonon-limited hole mobility Boltzmann transport equation

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Accurate and effective computation of the multi-phonon nonradiative transition

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Science China(Physics,Mechanics & Astronomy) 2020年第11期63卷 128-128页

作者： su-huai wei Beijing Computational Science Research Center Beijing 100193China

Nonradiative carrier recombination at a defect or impurity level can reduce the collection of photo-generated carriers and suppress ***,understanding the underlying mechanism and providing an accurate theoretical prediction of the carrier capture rate(CCR)of a defect in a semiconductor are important for both semiconductor physics and device engineering[1-5].

关键词： defect phonon radiative

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Profiling Electronic and Phononic Band Structures of Semiconductors at Finite Temperatures: Methods and Applications

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Chinese Physics Letters 2024年第2期41卷 57-68页

作者：张燮康俊魏苏淮 School of Materials Science and Engineering Northwestern Polytechnical UniversityXi’an 710072China Beijing Computational Science Research Center Beijing 100193China

Semiconductor devices are often operated at elevated temperatures that are well above zero Kelvin,which is the temperature in most first-principles density functional *** approaches to com-puting and understanding the properties of semiconductors at finite temperatures are thus in critical *** this review,we discuss the recent progress in computationally assessing the electronic and phononic band structures of semiconductors at finite *** an emerging semiconductor with particularly strong temperature-induced renormalization of the electronic and phononic band structures,halide perovskites are used as a representative example to demonstrate how computational advances may help to understand the band struc-tures at elevated ***,we briefly illustrate the remaining computational challenges and outlook promising research directions that may help to guide future research in this field.

关键词： Finite struc directions

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The origin of electronic band structure anomaly in topological crystalline insulator group-Ⅳ tellurides

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npj Computational Materials 2015年第1期1卷 32-37页

作者： Zhen-Yu Ye Hui-Xiong Deng Hui-Zhen Wu Shu-Shen Li su-huai wei Jun-wei Luo Department of Physics State Key Laboratory for Silicon MaterialsZhejiang UniversityHangzhouChina State Key Laboratory of superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijingChina National Renewable Energy Laboratory GoldenCOUSA.

Group-Ⅳ tellurides have exhibited exotic band ***,despite the fact that Sn sits between Ge and Pb in the same column of the periodic table,cubic SnTe is a topological crystalline insulator with band inversion,but both isovalent GeTe and PbTe are trivial semiconductors with normal band *** performing first-principles band structure calculations,we unravel the origin of this abnormal behaviour by using symmetry analysis and the atomic orbital energy levels and atomic sizes of these *** group-Ⅳ tellurides,the s lone pair band of the group-Ⅳ element is allowed by symmetry to couple with the anion valence p band at the L-point,and such s–p coupling leads to the occurrence of bandgap at the *** find that such s–p coupling is so strong in SnTe that it inverts the band order near the bandgap;however,it is not strong enough in both GeTe and PbTe,so they remain normal *** reason for this is the incomplete screening of the core of the relatively tight-binding Ge 4s orbital by its 3d orbitals and the large atomic size and strong relativistic effect in Pb,***,we also find that the rhombohedral distortion removes the inversion symmetry and the reduced s–p coupling transforms theα-SnTe back to a normal *** study demonstrates that,in addition to spin–orbital coupling,strain and interface dipole fields,inter-orbital coupling is another effective way to engineer the topological insulators.

关键词： topological orbital symmetry

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Atomic-Ordering-Induced Quantum Phase Transition between Topological Crystalline Insulator and Z_2 Topological Insulator

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Chinese Physics Letters 2018年第5期35卷 104-109页

作者： Hui-Xiong Deng Zhi-Gang Song Shu-Shen Li su-huai wei Jun-wei Luo State Key Laboratory of superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083 University of Chinese Academy of Sciences Beijing 100049 Beijing Academy of Quantum Information Sciences Beijing 100193 Beijing Computational Science Research Center Beijing 100094

Topological phase transition in a single material usually refers to transitions between a trivial band insulator and a topological Dirac phase, and the transition may also occur between different classes of topological Dirac *** is a fundamental challenge to realize quantum transition between Z_2 nontrivial topological insulator（TI） and topological crystalline insulator（TCI） in one material because Z_2 TI and TCI have different requirements on the number of band inversions. The Z_2 TIs must have an odd number of band inversions over all the time-reversal invariant momenta, whereas the newly discovered TCIs, as a distinct class of the topological Dirac materials protected by the underlying crystalline symmetry, owns an even number of band inversions. Taking PbSnTe_2 alloy as an example, here we demonstrate that the atomic-ordering is an effective way to tune the symmetry of the alloy so that we can electrically switch between TCI phase and Z_2 TI phase in a single material. Our results suggest that the atomic-ordering provides a new platform towards the realization of reversibly switching between different topological phases to explore novel applications.

关键词： Cu Te Sn TCI Atomic-Ordering-Induced Quantum Phase Transition between Topological Crystalline Insulator and Z2 Topological Insulator Pb Pt

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Prospect of Hexagonal CsMg(I_(1-x)Br_(x))_(3) Alloys for Deep-Ultraviolet Light Emission

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Chinese Physics Letters 2024年第9期41卷 52-56页

作者： Siyuan Xu Zheng Liu Xun Xu su-huai wei Yuzheng Guo Xie Zhang School of Electrical Engineering and Automation Wuhan UniversityWuhan 430072China Beijing Computational Science Research Center Beijing 100193China School of Materials Science and Engineering Northwestern Polytechnical UniversityXi’an 710072China

Materials for deep-ultraviolet(DUV)light emission are extremely rare,significantly limiting the development of efficient DUV light-emitting *** we report CsMg(I_(1−x)Br_(x))_(3) alloys as potential DUV light *** on rigorous first-principles hybrid functional calculations,we find that CsMgI_(3) has an indirect bandgap,while CsMgBr_(3) has a direct ***,we employ a band unfolding technique for alloy supercell calculations to investigate the critical Br concentration in CsMg(I_(1−x)Br_(x))_(3) associated with the crossover from an indirect to a direct bandgap,which is found to be∼***,CsMg(I_(1−x)Br_(x))_(3) alloys with 0.366≤6≤1 cover a wide range of direct bandgap(4.38–5.37 eV;284–231 nm),falling well into the DUV *** study will guide the development of efficient DUV light emitters.

关键词： alloys alloy Deep

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Strong Coupled Magnetic and Electric Ordering in Monolayer of Metal Thio(seleno)phosphates

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Chinese Physics Letters 2021年第7期38卷 145-150页

作者： Chenqiang Hua Hua Bai Yi Zheng Zhu-An Xu Shengyuan A.Yang Yunhao Lu su-huai wei Zhejiang Province Key Laboratory of Quantum Technology and Device State Key Laboratory of Silicon MaterialsDepartment of PhysicsZhejiang UniversityHangzhou 310027China Research Laboratory for Quantum Materials Singapore University of Technology and DesignSingapore 487372Singapore Beijing Computational Science Research Center Beijing 100193China

The coupling between electric ordering and magnetic ordering in two-dimensional(2D)materials is important for both fundamental research of 2D multiferroics and future development of magnetism-based information storage and ***,we introduce a scheme for realizing a magnetic phase transition through the transition of electric *** take CuMoP_(2)S_(6) monolayer as an example,which is a member of the large 2D transition-metal chalcogen-phosphates *** on first-principles calculations,we find that it is a multiferroic with unprecedented characters,namely,it exhibits two different phases:an antiferroelectric-antiferromagnetic phase and a ferroelectric-ferromagnetic phase,in which the electric and magnetic orderings are strongly ***,the electric polarization is out-of-plane,so the magnetism can be readily switched by using the gate electric *** finding reveals a series of 2D multiferroics with special magnetoelectric coupling,which hold great promise for experimental realization and practical applications.

关键词： ferroelectric coupling transition

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