Bilayer twisting as a mean to isolate connected flat bands in a kagome lattice through Wigner crystallization  

作　　者：Jing Wu Yue-E Xie Ming-Xing Chen Jia-Ren Yuan Xiao-Hong Yan Sheng-Bai Zhang Yuan-Ping Chen 吴静;谢月娥;陈明星;袁加仁;颜晓红;张绳百;陈元平(School of Physics and Optoelectronics,Xiangtan University,Xiangtan 411105,China;Faculty of Science,Jiangsu University,Zhenjiang 212013,China;School of Physics and Electronics,Hunan Normal University,Changsha 410081,China;Department of Physics,Applied Physics,and Astronomy Rensselaer Polytechnic Institute,Troy,New York 12180,USA)

机构地区：[1]School of Physics and Optoelectronics,Xiangtan University,Xiangtan 411105,China [2]Faculty of Science,Jiangsu University,Zhenjiang 212013,China [3]School of Physics and Electronics,Hunan Normal University,Changsha 410081,China [4]Department of Physics,Applied Physics,and Astronomy Rensselaer Polytechnic Institute,Troy,New York 12180,USA

出　　处：《Chinese Physics B》2021年第7期5-10,共6页中国物理B（英文版）

基　　金：the National Natural Science Foundation of China(Grant No.11874314);supported by U.S.DOE under Grant No.DE-SC0002623。

摘　　要：The physics of flat band is novel and rich but difficult to access.In this regard,recently twisting of bilayer van der Waals(vd W)-bounded two-dimensional(2 D)materials has attracted much attention,because the reduction of Brillouin zone will eventually lead to a diminishing kinetic energy.Alternatively,one may start with a 2 D kagome lattice,which already possesses flat bands at the Fermi level,but unfortunately these bands connect quadratically to other(dispersive)bands,leading to undesirable effects.Here,we propose,by first-principles calculation and tight-binding modeling,that the same bilayer twisting approach can be used to isolate the kagome flat bands.As the starting kinetic energy is already vanishingly small,the interlayer vd W potential is always sufficiently large irrespective of the twisting angle.As such the electronic states in the(connected)flat bands become unstable against a spontaneous Wigner crystallization,which is expected to have interesting interplays with other flat-band phenomena such as novel superconductivity and anomalous quantum Hall effect.

关 键 词：twisted bilayer kagome graphene flat bands Wigner crystallization 

分 类 号：O469[理学—凝聚态物理]