二维莫尔超晶格中的非线性霍尔效应  

Nonlinear Hall effects in two-dimensional moirésuperlattices

作　　者：吴泽飞 黄美珍 王宁[1] Wu Ze-Fei;Huang Mei-Zhen;Wang Ning(Department of Physics,The Hong Kong University of Science and Technology,Hong Kong 999077,China;Department of Physics and Astronomy and the National Graphene Institute,University of Manchester,Manchester M139PL,UK)

机构地区：[1]香港科技大学物理系,中国香港999077 [2]曼彻斯特大学物理与天文系及英国国家石墨烯中心,英国曼彻斯特M139PL

出　　处：《物理学报》2023年第23期232-249,共18页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2020YFA0309600);香港研究资助局(批准号:AoE/P-701/20,16303720,HKUST C6008-20E)资助的课题。

摘　　要：1879年发现的霍尔效应是凝聚态物理学中最古老也是最重要的领域之一.最近发现的非线性霍尔效应是霍尔效应家族的新成员.与大部分需要打破时间反演对称的霍尔效应不同,非线性霍尔效应存在于少数空间反演破缺但仍具有时间反演对称的系统中,并且因其高频特性和不需额外施加磁场而在诸多领域具有令人期待的应用前景.然而,除空间反演破缺以外,非线性霍尔效应对材料对称性的要求十分苛刻,只在极少数材料中观测到了由贝里曲率偶极矩产生的非线性霍尔效应.近年来快速发展的范德瓦耳斯堆叠技术为剪裁和调控晶体的对称性,制备具有特殊物理性质的人工二维莫尔晶体提供了一个崭新的途径.本文主要围绕二维莫尔超晶格结构在实现非线性霍尔效应方面的特性,介绍了近年来理论和实验上石墨烯超晶格以及过渡金属硫族化合物超晶格中非线性霍尔效应的研究进展,并展望了未来基于二维莫尔超晶格材料的非线性霍尔效应的研究方向和应用前景.The Hall effect refers to the generation of a voltage in a direction perpendicular to the applied current.Since its discovery in 1879,the Hall effect family has become a huge group,and its in-depth study is an important topic in the field of condensed matter physics.The newly discovered nonlinear Hall effect is a new member of Hall effects.Unlike most of previous Hall effects,the nonlinear Hall effect does not need to break the time-reversal symmetry of the system but requires the spatial inversion asymmetry.Since 2015,the nonlinear Hall effect has been predicted and observed in several kinds of materials with a nonuniform distribution of the Berry curvature of energy bands.Experimentally,when a longitudinal alternating current(AC)electric field is applied,a transverse Hall voltage will be generated,with its amplitude proportional to the square of the driving current.Such a nonlinear Hall signal contains two components:one is an AC transverse voltage oscillating at twice the frequency of the driving current,and the other is a direct current(DC)signal converted from the injected current.Although the history of the nonlinear Hall effect is only a few years,its broad application prospects in fields of wireless communication,energy harvesting,and infrared detectors have been widely recognized.The main reason is that the frequency doubling and rectification of electrical signals via some nonlinear Hall effects are achieved by an inherent quantum property of the material-the Berry curvature dipole moment,and therefore do not have the thermal voltage thresholds and/or the transition time characteristic of semiconductor junctions/diodes.Unfortunately,the existence of the Berry curvature dipole moment has more stringent requirements for the lattice symmetry breaking of the system apart from the spatial inversion breaking,and the materials available are largely limited.This greatly reduces the chance to optimize the signal of the nonlinear Hall effect and limits the application and development of the nonlinear Hall effect.

关 键 词：非线性霍尔 莫尔超晶格 二维材料 贝里曲率偶极矩 

分 类 号：O73[理学—晶体学] O469