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Topological magnetoelectric response in ferromagnetic axion insulators

National Science Review 2024年第2期11卷 8-14页

作者： Yuhao Wan Jiayu Li Qihang Liu Department of Physics and Shenzhen Institute for Quantum Science and Engineering(SIQSE) Southern University of Science and Technology Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices Southern University of Science and Technology Guangdong Provincial Key Laboratory for Computational Science and Material Design Southern University of Science and Technology

The topological magnetoelectric effect （TME） is a hallmark response of the topological field theory,which provides a paradigm shift in the study of emergent topological ***,its direct observation is yet to be realized due to the demanding magnetic configuration required to gap all surface ***,we theoretically propose that axion insulators with a simple ferromagnetic configuration,such as the MnBi2Te4/（Bi2Te3）nfamily,provide an ideal playground to realize the *** the designed triangular prism geometry,all the surface states are magnetically *** a vertical electric field,the surface Hall currents give rise to a nearly half-quantized orbital moment,accompanied by a gapless chiral hinge mode circulating in ***,the orbital magnetization from the two topological origins can be easily distinguished by reversing the electric *** work paves the way for direct observation of the TME in realistic axion-insulator materials.

关键词： topological magnetoelectric effect axion insulator magnetic topological materials

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Enhanced reconstruction of Fe_(5)Ni_(4)S_(8) by implanting pyrrolidone to unlock efficient oxygen evolution

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Journal of Energy Chemistry 2023年第9期84卷 112-121页

作者： Zhengyan Du Zeshuo Meng Chao Jiang Chenxu Zhang Yanan Cui Yaxin Li Chong Wang Xiaoying Hu Shansheng Yu Hongwei Tian Key Laboratory of Automobile Materials of MOE School of Materials Science and EngineeringJilin UniversityChangchun 130012JilinChina College of Science and Laboratory of Materials Design and Quantum Simulation Changchun UniversityChangchun 130022JilinChina

During oxygen evolution reaction(OER),complex changes have been reported on surfaces of bimetallic Fe-Ni-based catalysts,and regulating the dynamic evolution could improve their electrocatalytic ***,a pyrrolidone-promoted reconstruction of pentlandite was investigated to uncover the correlation between the reconstructed surface and the OER *** theoretical calculations indicated the preferential implantation of pyrrolidone at Fe atoms,useful for regulating the electronic structures of *** vale nce state of Ni increased,suggesting the promotion of the in-situ reconstruction of pentlandite via strengthening hydroxyl adsorption to generate highly active *** electron-rich pentlandite was also found conducive to charge transfer under applied *** Operando Raman and various quasi-in-situ characterizations confirmed the realization of more delocalized electronic structures of pentlandite by introducing ***,in turn,promoted the accumulation of hydroxyl groups on the pentlandite surface,thereby boosting the formation of highly active NiOOH at lower OER ***,the adsorption energies of intermediates were optimized,conducive to enhanced OER reaction *** a proof of concept,the pentlandite decorated by pyrrolidone exhibited an overpotential as low as 265 mV at 10 mA cm^(-2) coupled with stable catalysis for 1000 hours at a high current density of 100 mA cm^(-2).In sum,new insights into unlocking the high catalytic activity of bimetallic Fe-Ni-based catalysts were provided,promising for future synthesis of advanced catalysts.

关键词： Pentlandite Oxygen evolution reaction Reconstruction ability Catalytic kinetics

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Layer Hall effect induced by hidden Berry curvature in antiferromagnetic insulators

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National Science Review 2024年第2期11卷 15-23页

作者： Rui Chen Hai-Peng Sun Mingqiang Gu Chun-Bo Hua Qihang Liu Hai-Zhou Lu X.C.Xie Shenzhen Institute for Quantum Science and Engineering and Department of Physics Southern University of Science and Technology(SUSTech) International Quantum Academy Institute for Theoretical Physics and Astrophysics University of Würzburg School of Electronic and Information Engineering Hubei University of Science and Technology Guangdong Provincial Key Laboratory of Computational Science and Material Design Southern University of Science and Technology Shenzhen Key Laboratory of Quantum Science and Engineering International Center for Quantum Materials School of PhysicsPeking University Collaborative Innovation Center of Quantum Matter CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences

The layer Hall effect describes electrons spontaneously deflected to opposite sides at different layers, which has been experimentally reported in the MnBi2Te4thin films under perpendicular electric fields. Here, we reveal a universal origin of the layer Hall effect in terms of the so-called hidden Berry curvature, as well as material design principles. Hence, it gives rise to zero Berry curvature in momentum space but non-zero layer-locked hidden Berry curvature in real space. We show that, compared to that of a trivial insulator, the layer Hall effect is significantly enhanced in antiferromagnetic topological insulators. Our universal picture provides a paradigm for revealing the hidden physics as a result of the interplay between the global and local symmetries, and can be generalized in various scenarios.

关键词： layerHall effect hidden Berry curvature antiferromagnetic insulator axion insulator, quantum transport

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Rational design of large anomalous Nernst effect in Dirac semimetals

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npj Computational materials 2023年第1期9卷 258-264页

作者： Panshuo Wang Zongxiang Hu Xiaosong Wu Qihang Liu Shenzhen Institute for Quantum Science and Engineering and Department of Physics Southern University of Science and Technology518055 ShenzhenChina State Key Laboratory for Artificial Microstructure and Mesoscopic Physics Frontiers Science Center for Nano-optoelectronicsand Collaborative Innovation Center of Quantum MatterPeking University100871 BeijingChina Guangdong Provincial Key Laboratory of Computational Science and Material Design Southern University of Science and Technology518055 ShenzhenChina Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices Southern University of Science and Technology518055 ShenzhenChina

Anomalous Nernst effect generates a transverse voltage perpendicular to the temperature *** has several advantages compared with the longitudinal thermoelectricity for energy conversion,such as decoupling of electronic and thermal transports,higher flexibility,and simpler lateral ***,a design principle beyond specific materials systems for obtaining a large anomalous Nernst conductivity(ANC)is still *** this work,we theoretically demonstrate that a pair of Dirac nodes under a Zeeman field manifests an odd-distributed,double-peak anomalous Hall conductivity curve with respect to the chemical potential and a compensated carrier feature,leading to an enhanced ANC compared with that of a simple Weyl semimetal with two Weyl *** on first-principles calculations,we then provide two Dirac semimetal candidates,i.e.,Na3Bi and NaTeAu,and show that under a Zeeman field,they exhibit a sizable ANC value of 0.4 Am^(-1)K^(-1) and 1.3 Am^(-1)K^(-1),respectively,near the Fermi *** an approach is also applicable to ferromagnetic materials with intrinsic Zeeman splitting,as exemplified by a hypothetical alloy NaFeTe2Au2,exhibiting an ANC as high as 3.7 Am^(-1)K^(-1) at the Fermi *** work provides a design principle with a prototype band structure for enhanced ANC pinning at the Fermi level,shedding light on the inverse design of other specific functional materials based on electronic structure.

关键词： structure Nernst Dirac

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Group Theory on Quasisymmetry and Protected Near Degeneracy

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Physical Review Letters 2024年第2期133卷 026402-026402页

作者： Jiayu Li Ao Zhang Yuntian Liu Qihang Liu Department of Physics and Shenzhen Institute for Quantum Science and Engineering (SIQSE) Guangdong Provincial Key Laboratory for Computational Science and Material Design Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices

In solid state systems, group representation theory is powerful in characterizing the behavior of quasiparticles, notably the energy degeneracy. While conventional group theory is effective in answering yes-or-no questions related to symmetry breaking, its application to determining the magnitude of energy splitting resulting from symmetry lowering is limited. Here, we propose a theory on quasisymmetry and near degeneracy, thereby expanding the applicability of group theory to address questions regarding large-or-small energy splitting. Defined within the degenerate subspace of an unperturbed Hamiltonian, quasisymmetries form an enlarged symmetry group eliminating the first-order splitting. This framework ensures that the magnitude of splitting arises as a second-order effect of symmetry-lowering perturbations, such as external fields and spin-orbit coupling. We systematically tabulate the quasisymmetry groups within 32 crystallographic point groups and find all the possible unitary quasisymmetry group structures regarding double degeneracy. Applying our theory to the realistic material AgLa, we predict a “quasi-Dirac semimetal” phase characterized by two tiny-gap band anticrossings.

关键词： Electronic structure Topological materials Density functional theory Group theory

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Pressure-stabilized electride Li10Si with superconducting and superionic behavior

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Physical Review B 2024年第13期110卷 134114页

作者： Qinfang Wang Wenwen Cui Weishuo Xu Kun Gao Jian Hao Jingming Shi Hanyu Liu Yinwei Li Laboratory of Quantum Functional Materials Design and Application School of Physics and Electronic Engineering Key Laboratory of Material Simulation Methods and Software of Ministry of Education and State Key Laboratory of Superhard Materials College of Physics Shandong Key Laboratory of Optical Communication Science and Technology School of Physical Science & Information Technology of

Electrides have attracted increasing interest due to their diversely physical properties, including low work function, high catalytic activity, as well as potential superconductivity. In this work, using first-principles crystal structure prediction method in combination with first-principles calculations, we uncovered seven thermodynamically stable electrides in the electron-rich Li-Si system at a pressure range of 25–100 GPa, namely C2/cLi5Si, CmcmLi6Si, P21/mLi7Si, ImmaLi7Si, C2/cLi8Si, CmcmLi9Si, and I222Li10Si. Among these predicted structures, five of them are superconductor. In particular, the superconducting critical temperature Tc of I222Li10Si was estimated to be approximately 15 K at 95 GPa. Our in-depth analysis shows that this high superconductivity is attributed to the strong coupling between the Li-p electrons and the Li-dominated phonon softening at low frequencies. Additionally, Li10Si undergoes a phase transition from solid state to superionic state at 60 GPa and 850 K, where Si atoms remain fixed to form the lattice, allowing for the diffusion of Li atoms within the interstitial position. Our results reveal the emergence of two distinct dynamic states of superconducting and superionic in this particular system, and the further experimental studies are thus stimulated.

关键词： Superconductors Density functional calculations Density functional theory First-principles calculations

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Sodium chloride induced nitrogen salt with cyclo-N5 anions at high pressure

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Physical Review Research 2024年第3期6卷 033213页

作者： Bi Zhang Meiling Xu Yu Xin Shuyi Lin Jian Hao Yanchao Wang Yinwei Li Laboratory of Quantum Functional Materials Design and Application School of Physics and Electronic Engineering Key Laboratory of Material Simulation Methods and Software of Ministry of Education and State Key Laboratory of Superhard Materials College of Physics Department of Applied Physics The

The energy landscape of sodium chloride-nitrogen mixtures has been comprehensively explored to examine the ability of the formation of unknown compounds under pressures of up to 100 GPa, using swarm-intelligence structure prediction methodology and first-principles calculations. We identified a thermodynamically stable NaN5ClN5 compound containing two cyclo-N5 species under pressures exceeding 53 GPa, representing milder conditions in comparison to those requisite for pure solid nitrogen. In NaN5ClN5, the high electron affinity of the cyclo-N5 motif allows it to oxidize the chlorine atoms, resulting in the formation of two cyclo-N5 anions. Additionally, the weak covalent interactions between Cl and nearby N atoms plays a key role in stabilization of structure. It has been demonstrated that simple NaN5 salt was a suitable precursor for the synthesis of NaN5ClN5 at high pressure. Ab initio molecular dynamics simulations demonstrated the recoverability of NaN5ClN5 as a metastable phase at ambient pressure-temperature conditions. Additionally, NaN5ClN5 exhibits a higher energy density of 3.86 kJ/g and a lower mass density of 1.67 g/cm3 in comparison to metal pentazolate salts, highlighting its potential as a high energy-density material.

关键词： First-principles calculations Energy materials

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Prediction of high-Tc superconductivity under submegabar pressure in ternary actinium borohydrides

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Physical Review B 2024年第6期110卷 064105页

作者： Tingting Gu Wenwen Cui Jian Hao Jingming Shi Artur P. Durajski Hanyu Liu Yinwei Li Laboratory of Quantum Functional Materials Design and Application School of Physics and Electronic Engineering Institute of Physics Key Laboratory of Material Simulation Methods and Software of Ministry of Education and State Key Laboratory of Superhard Materials College of Physics

Ternary hydrides are considered as the ideal candidates with high critical temperature (Tc) stabilized at submegabar pressure, evidenced by the recent discoveries in LaBeH8 (110 K at 80 GPa) and LaB2H8 (106 K at 90 GPa). Here, we investigate the crystal structures and superconductivity of an Ac-B-H system under pressures of 100 and 200 GPa by using an advanced structure method combined with first-principles calculations. As a result, nine stable compounds were identified, where B atoms are bonded with H atoms in the formation with diverse BHx motifs, e.g., methanelike (BH4), polythenelike, (BH2)n, and BH6 octahedron. Among them, seven Ac-B-H compounds were found to become superconductive. In particular, AcBH7 was estimated to have a Tc of 122 K at 70 GPa. Our in-depth analysis reveals that the B-H interactions in the BH6 units play a key role in its high superconductivity and stability at submegabar pressure. Our current results provide a guidance for future experiments to synthesize ternary hydride superconductors with high-Tc at moderate pressure.

关键词： Density of states First-principles calculations Crystal structures High-temperature superconductors Hydrides Superconductivity

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Enumeration and Representation Theory of Spin Space Groups

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Physical Review X 2024年第3期14卷 031038页

作者： Xiaobing Chen Jun Ren Yanzhou Zhu Yutong Yu Ao Zhang Pengfei Liu Jiayu Li Yuntian Liu Caiheng Li Qihang Liu Department of Physics and Shenzhen Institute for Quantum Science and Engineering National Center for Applied Mathematics Shenzhen and Department of Mathematics Guangdong Provincial Key Laboratory of Computational Science and Material Design Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices

Fundamental physical properties, such as phase transitions, electronic structures, and spin excitations, in all magnetic ordered materials, were ultimately believed to rely on the symmetry theory of magnetic space groups. Recently, it has come to light that a more comprehensive group, known as the spin space group (SSG), which combines separate spin and spatial operations, is necessary to fully characterize the geometry and underlying properties of magnetic ordered materials. However, the basic theory of SSG has seldom been developed. In this work, we present a systematic study of the enumeration and the representation theory of the SSG. Starting from the 230 crystallographic space groups and finite translation groups with a maximum order of eight, we establish an extensive collection of over 100 000 SSGs under a four-index nomenclature as well as international notation. We then identify inequivalent SSGs specifically applicable to collinear, coplanar, and noncoplanar magnetic configurations. To facilitate the identification of the SSG, we develop an online program that can determine the SSG symmetries of any magnetic ordered crystal. Moreover, we derive the irreducible corepresentations of the little group in momentum space within the SSG framework. Finally, we illustrate the SSG symmetries and physical effects beyond the framework of magnetic space groups through several representative material examples, including a candidate altermagnet RuO2, spiral spin polarization in the coplanar antiferromagnet CeAuAl3, and geometric Hall effect in the noncoplanar antiferromagnet CoNb3S6. Our work advances the field of group theory in describing magnetic ordered materials, opening up avenues for deeper comprehension and further exploration of emergent phenomena in magnetic materials.

关键词： Electronic structure Magnetic order Spin texture Noncollinear magnets Density functional theory Group theory

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Realizing the air brazing of ZrO_(2) ceramics through Al metal

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Journal of Materiomics 2022年第3期8卷 662-668页

作者： Yaotian Yan Baishen Liu Tianxiong Xu Liang Qiao Shaohua Qin Jian Cao Junlei Qi State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin150001China Key Laboratory of Materials Design and Quantum Simulation College of ScienceChangchun UniversityChangchun130022China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin150001China

The exploration towards cost-effective filler metal for ceramics joining has always been the key issues for ceramics ***,we reveal that the Al metal prefers to spread on the ZrO_(2) based ceramic under the air heating condition,due to the geometric limit effects by in-situ formed dense Al2O3 *** by this,the joining of ZrO_(2) based ceramics was realized in air with Al metal as filler,through the diffusion of Al towards ceramic *** Al element can induce obvious interfacial bonding effect on Al2O3 layer and ZrO_(2) ceramic,where the hybridization among the Al-p,Zr-d and O-p orbitals plays a key *** in-situ formed Al2O3 layer on Al filler surface is vital for forming the fine interface(shear strength of~36 MPa),which results in the relief of lattice mismatch and peak stress at ceramic-filler metal transition interface.

关键词： Ceramics Density functional theory Interfacial behavior Diffusion

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