摘要
电子空穴在库仑相互作用下会发生从半金属态到激子基态的相变,在费米面附近自发打开能隙,该基态被称为激子绝缘体.该物态在凝聚态物理领域吸引了广泛的关注,相关的实验证据一直在寻找中.近年来,在浅反转InAs/GaSb量子阱中,激子绝缘体的光学能谱和输运特征首先被观察到,证实了激子绝缘体在二维体系中的存在.令人意外的是,在这一激子绝缘态中,电学输运测量探测到了对磁场和温度不敏感的一维类螺旋拓扑边缘态.这一观察到的激子基态很难用现有的单粒子理论进行解释,被称为拓扑激子绝缘体.本文系统回顾了在该量子阱中针对拓扑激子绝缘体的实验研究,包括电学输运、太赫兹透射谱、电容测量等.这些实验结果综合表征了拓扑激子绝缘体的体态与边缘态性质.拓扑激子绝缘体作为一个由玻色子构成的基态,在极限条件下有望相变为具有宏观相干性的玻色爱因斯坦凝聚态,为研究低维电子相互作用提供新的平台.
Under Coulomb interactions,electrons and holes have a phase transition from a semi-metal state into an excitonic ground state,with a gap spontaneously opening at the Fermi level.The excitonic ground state is called excitonic insulator.The excitonic insulator has attracted extensive attention in condensed matter physics,but the experimental evidence of such a quantum state is still under search.Until recent years,optical spectral and transport evidence of the excitonic insulator has first been observed in shallowly inverted InAs/GaSb quantum wells,which confirms the existence of the exciton insulator in a two-dimensional system.Surprisingly,one-dimensional helical-like topological edge states,which are not sensitive to temperature nor magnetic field,have been observed in the excitonic insulator state by transport measurements.This new quantum phase cannot be well explained by existing single-particle theories,which is called a topological excitonic insulator.In this paper,we systematically review the experimental studies on the topological excitonic insulator in the InAs quantum well and GaAs quantum well,including magneto transport,terahertz transmission,capacitance,and Coulomb drag measurements.These experimental results comprehensively characterize the bulk properties and edge properties of the topological excitonic insulator.Furthermore,as a ground state consisting of bosons,the topological excitonic insulator is expected to have a quantum phase transition into Bose-Einstein condensate with macroscopic coherence under extreme conditions,which provides a new platform for studying the quantum phenomena of Coulomb interactions in low dimensions.
作者
黄月蕾
单寅飞
杜灵杰
杜瑞瑞
Huang Yue-Lei;Shan Yin-Fei;Du Ling-Jie;Du Rui-Rui(National Laboratory of Solid State Microstructures,School of Physics,Nanjing University,Nanjing 210093,China;International Center for Quantum Materials,School of Physics,Peking University,Beijing 100871,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2023年第17期1-13,共13页
Acta Physica Sinica
基金
国家自然科学基金(批准号:12074177,11921005)
国家重点基础研究发展计划(批准号:2019YFA0308400)
中国科学院战略性先导专项(批准号:XDB28000000)资助的课题.
关键词
激子绝缘体
量子阱
边缘态
excitonic insulator
quantum well
edge states
