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Valence bands Convergence in p-Type CoSb_(3) through Electronegative Fluorine Filling

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Chinese Physics Letters 2024年第7期41卷 87-94页

作者：黄写格李家良马浩钦李昌隆刘天乐段波翟鹏程李国栋 Hubei Key Laboratory of Theory and Application of Advanced Materials Mechanics Wuhan University of TechnologyWuhan 430070China School of Civil Engineering&Architecture Wuhan Polytechnic UniversityWuhan 430023China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China

Band convergence is considered to be a strategy with clear benefits for thermoelectric performance,generally favoring the co-optimization of conductivity and Seebeck coefficients,and the conventional means include elemental filling to regulate the ***,the influence of the most electronegative fluorine on the CoSb_(3) band remains *** carry out density-functional-theory calculations and show that the valence band maximum gradually shifts downward with the increase of fluorine filling,lastly the valence band maximum converges to the highly degenerated secondary valence bands in fluorine-filled skutterudites.

关键词： valence Convergence bands

Moiré potential renormalization and ultra-flat bands induced by quasiparticle-plasmon coupling

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npj Computational Materials 2023年第1期9卷 2279-2285页

作者： Linghan Zhu Haonan Wang Li Yang Department of Physics Washington University in St.LouisSt.LouisMO 63130USA Institute of Materials Science and Engineering Washington University in St.LouisSt.LouisMO 63130USA

Moirépotential profile can form flat electronic bands and manifest correlated states of electrons,where carrier doping is essential for observing those *** this work,we uncover a hidden but remarkable many-electron effect:doped carriers form a two-dimensional plasmon and strongly couple with quasiparticles to renormalize moirépotential and realize ultra-flat *** many-body perturbation theory,we demonstrate this effect in twisted MoS_(2)/WS_(2) *** moirépotential is significantly enhanced upon carrier doping,and the bandwidth is reduced by order of magnitude,leading to drastic quenching of electronic kinetic energy and stronger *** further predict that the competition between correlated mechanisms can be effectively controlled via doping,giving hope to a quantum transition between Mott and charge-transfer insulating *** work reveals that the potential renormalization effect of doping is much more significant in determining and controlling many-electron electronic correlations than sole filling-factor tuning in semiconducting moirécrystals.

关键词： bands doping potential

Point-defect-driven flattened polar phonon bands in fluorite ferroelectrics

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npj Computational Materials 2023年第1期9卷 1120-1128页

作者： Pu Ai Fengjun Yan Wen Dong Shi Liu Junlei Zhao Kan-Hao Xue Syed Ul Hasnain Bakhtiar Yilong Liu Qi Ma Ling Miao Mengyuan Hua Guangzu Zhang Shenglin Jiang Wei Luo Qiuyun Fu School of Integrated Circuits Engineering Research Centre for Functional Ceramics of the Ministry of Education&Wuhan National Lab for Optoelectronics&Optical Valley Laboratory Huazhong University of Science and Technology430074 WuhanChina Department of Physics School of ScienceWestlake UniversityHangzhou310024 ZhejiangChina School of Optical and Electronic Information Research Centre&Wuhan National Lab for Optoelectronics&Optical Valley Laboratory Huazhong University of Science and Technology430074 WuhanChina Department of Electrical and Electronic Engineering Southern University of Science and Technology518055 ShenzhenChina Shenzhen Huazhong University of Science and Technology Research Institute 518000 ShenzhenP.R.China

The scale-free ferroelectric polarization of fluorite MO_(2)(M=Hf,Zr)due to flat polar phonon bands are promising for nonvolatile *** are also widely introduced to improve the emergent ***,their roles are still not fully understood at the ***,we report a significant effect of point-defect-driven flattening of polar phonon bands with more polar modes and polarization contribution in doped MO_(2).The polar phonon bands in La-doped MO_(2)(M=Hf,Zr)can be significantly flattened,compared with pure ***,the lower energy barrier with larger polarization of VO-only doped MO_(2) compared with La-doped cases suggest that VO and local lattice distortion should be balanced for high-performance fluorite *** work is believed to bridge the relation between point defects and the generally enhanced induced ferroelectricity in fluorite ferroelectrics at the atomic-level and inspire their further property optimization via defect-engineering.

关键词： bands phonon ferroelectric

Alternating twisted multilayer graphene:generic partition rules,double flat bands,and orbital magnetoelectric effect

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npj Computational Materials 2022年第1期8卷 1037-1044页

作者： Bo Xie Ran Peng Shihao Zhang Jianpeng Liu School of Physical Science and Technology ShanghaiTech UniversityShanghai201210China ShanghaiTech Laboratory for Topological Physics ShanghaiTech UniversityShanghai201210China

Recently the alternating twisted trilayer graphene is discovered to exhibit unconventional superconductivity,which motivates us to study the electronic structures and possible correlation effects for this class of alternating twisted multilayer graphene(ATMG)*** this work we consider generic ATMG systems with M-L-N stacking configurations,in which the M(L)graphene layers and the L(N)layers are twisted by an angleθ(−θ).Based on analysis from a simplified k⋅p model approach,we derive generic partition rules for the low-energy electronic structures,which exhibit various band dispersions including two pairs of flat bands and flat bands co-existing with various gapless Fermionic *** a mirror-symmetric ATMG system with doubled flat bands,we further find that Coulomb interactions may drive the system into a state with intertwined electric polarization and orbital magnetization orders,which can exhibit an interaction-driven orbital magnetoelectric effect.

关键词： twisted bands orbital

Doubled Moiré fat bands in double-twisted few-layer graphite

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Science China(Physics,Mechanics & Astronomy) 2023年第2期66卷 95-101页

作者： Zhen Ma Shuai Li Ming Lu Dong-Hui Xu Jin-Hua Gao XinCheng Xie School of Physics Wuhan National High Magnetic Field CenterHuazhong University of Science and TechnologyWuhan 430074China Beijing Academyof Quantum Information Sciences Beijing100193China International Center for Quantum Materials School of PhysicsPeking UniversityBeijing 100871China Department of Physics and Chongqing Key Laboratory for Strongly Coupled Physics Chongqing UniversityChongqing 400044China Center of Quantum Materials and Devices Chongqing UniversityChongqing 400044China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190China

We study the electronic structure of double-twisted few-layer graphite(DTFLG),which consists of three few-layer graphites(FLGs),i.e.,an ABA-stacked graphene multilayer,stacked with two twist *** consider two categories of DTFLG,the alternately and chirally twisted cases,according to the rotation direction of the two twist *** show that,once the middle FLG of DTFLG is not thinner than the trilayer,both types of DTFLG can remarkably host two pairs of degenerate Moire flat bands(MFBs) at EF,twice that of the magic angle twisted bilayer graphene(TBG).The doubled MFBs of DTFLG lead to a doubled density of states(DOS) at the Fermi level EF,which implies much stronger correlation effects than *** degeneracy of MFBs can be lifted by a perpendicular electric field,and the isolated MFBs have a nonzero valley Chern *** also reveal the peculiar wave function patterns of the MFB s in *** results establish a new family of Moire systems that have a much higher DOS at EFand thus possibly much stronger correlation effects.

关键词： twisted bands doubled

Strong interlayer coupling and stable topological flat bands in twisted bilayer photonic Moiré superlattices

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Light(Science & Applications) 2022年第10期11卷 2523-2529页

作者： Chang-Hwan Yi Hee Chul Park Moon Jip Park Center for Theoretical Physics of Complex Systems Institute for Basic Science(IBS)Daejeon 34126Republic of Korea

The moiré superlattice of misaligned atomic bilayers paves the way for designing a new class of materials with wide *** this work,we propose a photonic analog of the moiré superlattice based on dielectric resonator *** sharp contrast to van der Waals materials with weak interlayer coupling,we realize the strong coupling regime in a moiré superlattice,characterized by cascades of robust flat bands at large ***,we find that these flat bands are characterized by a non-trivial band topology,the origin of which is the moiré pattern of the resonator *** physical manifestation of the flat band topology is a robust one-dimensional conducting channel on edge,protected by the reflection symmetry of the moiré *** explicitly breaking the underlying reflection symmetry on the boundary terminations,we show that the first-order topological edge modes naturally deform into higher-order topological corner *** work pioneers the physics of topological phases in the designable platform of photonic moiré superlattices beyond the weakly coupled regime.

关键词： topological bands coupling

Realization of^(87)Rb Bose–Einstein Condensates in Higher bands of a Hexagonal Boron-Nitride Optical Lattice

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Chinese Physics Letters 2023年第8期40卷 53-57页

作者：刘金玉王小琼许志芳 Department of Physics Harbin Institute of TechnologyHarbin 150001China Department of Physics Southern University of Science and TechnologyShenzhen 518055China Shenzhen Institute for Quantum Science and Engineering Southern University of Science and TechnologyShenzhen 518055China

Ultracold neutral atoms in higher bands of an optical lattice provide a natural avenue to emulate orbital physics in solid state ***,we report the realization of^(87)Rb Bose-Einstein condensates in the fourth and seventh Bloch bands of a hexagonal boron-nitride optical lattice,exhibiting remarkably long coherence time through active *** band mapping spectroscopy,we observe that atoms condensed at the energy minimum of L point(K_(1)and K_(2)points)in the fourth(seventh)band as sharp Bragg *** lifetime for the condensate in the fourth(seventh)band is about 57.6(4.8)ms,and the phase coherence of atoms in the fourth band persists for a long time larger than 110 *** work thus offers great promise for studying unconventional bosonic superfluidity of neutral atoms in higher bands of optical lattices.

关键词： materials bands Einstein

Intrinsic superflat bands in general twisted bilayer systems

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Light(Science & Applications) 2022年第7期11卷 1475-1481页

作者： Hongfei Wang Shaojie Ma Shuang Zhang Dangyuan Lei Department of Materials Science and Engineering City University of Hong KongKowloonHong Kong 999077China Department of Physics University of Hong KongHong Kong 999077China Department of Electrical and Electronic Engineering University of Hong KongHong Kong 999077China

Twisted bilayer systems with discrete magic angles,such as twisted bilayer graphene featuring moirésuperlattices,provide a versatile platform for exploring novel physical ***,we discover a class of superflat bands in general twisted bilayer systems beyond the low-energy physics of magic-angle twisted *** considering continuous lattice dislocation,we obtain intrinsic localized states,which are spectrally isolated at lowest and highest energies and spatially centered around the AA stacked region,governed by the macroscopic effective energy potential *** localized states exhibit negligible inter-cell coupling and support the formation of superflat bands in a wide and continuous parameter space,which can be mimicked using a twisted bilayer nanophotonic *** finding suggests that general twisted bilayer systems can realize continuously tunable superflat bands and the corresponding localized states for various photonic,phononic,and mechanical waves.

关键词： properties. twisted bands

Optimal band structure for thermoelectrics with realistic scattering and bands

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npj Computational Materials 2021年第1期7卷 388-396页

作者： Junsoo Park Yi Xia Vidvuds Ozoliņš Anubhav Jain Energy Technologies Area Lawrence Berkeley National LaboratoryBerkeleyCAUSA Department of Materials Science and Engineering Northwestern UniversityEvanstonILUSA Department of Applied Physics Yale UniversityNew HavenCTUSA Energy Sciences Institute Yale UniversityWest HavenCTUSA

Understanding how to optimize electronic band structures for thermoelectrics is a topic of long-standing interest in the *** models have been limited to simplified bands and/or scattering *** this study,we apply more rigorous scattering treatments to more realistic model band structures—upward-parabolic bands that inflect to an inverted-parabolic behavior—including cases of multiple *** contrast to common descriptors(e.g.,quality factor and complexity factor),the degree to which multiple pockets improve thermoelectric performance is bounded by interband scattering and the relative shapes of the *** establish that extremely anisotropic“flat-and-dispersive”bands,although best-performing in theory,may not represent a promising design strategy in ***,we determine optimum bandwidth,dependent on temperature and lattice thermal conductivity,from perfect transport cutoffs that can in theory significantly boost zT beyond the values attainable through intrinsic band structures *** analysis should be widely useful as the thermoelectric research community eyes zT>3.

关键词： bands parabolic apply