Tunable correlation in twisted monolayer–trilayer graphene  

作　　者：丁冬冬 牛锐锐 韩香岩 曲壮壮 王知雨 李卓贤 刘倩伶 韩春蕊 路建明 Dongdong Ding;Ruirui Niu;Xiangyan Han;Zhuangzhuang Qu;Zhiyu Wang;Zhuoxian Li;Qianling Liu;Chunrui Han;Jianming Lu(State Key Laboratory for Mesoscopic Physics,School of Physics,Peking University,Beijing 100871,China;Institute of Microelectronics,Chinese Academy of Sciences,Beijing 100029,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]State Key Laboratory for Mesoscopic Physics,School of Physics,Peking University,Beijing 100871,China [2]Institute of Microelectronics,Chinese Academy of Sciences,Beijing 100029,China [3]University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Chinese Physics B》2023年第6期96-101,共6页中国物理B（英文版）

基　　金：support from the National Natural Science Foundation of China(Grant No.11974027);the National Key R&D Program of China(Grant Nos.2019YFA0307800 and 2021YFA1400100);Beijing Natural Science Foundation(Grant No.Z190011);Beijing Natural Science Foundation(Grant No.4222084);support from the National Natural Science Foundation of China(Grant No.62275265)。

摘　　要：Flat-band physics of moirésuperlattices,originally discovered in the celebrated twisted bilayer graphene,have recently been intensively explored in multilayer graphene systems that can be further controlled by electric field.In this work,we experimentally find the evidence of correlated insulators at half filling of the electron moiréband of twisted monolayer–trilayer graphene with a twist angle around 1.2°.Van Hove singularity(VHS),manifested as enhanced resistance and zero Hall voltage,is observed to be distinct in conduction and valence flat bands.It also depends on the direction and magnitude of the displacement fields,consistent with the asymmetric crystal structure.While the resistance ridges at VHS can be enhanced by magnetic fields,when they cross commensurate fillings of the moirésuperlattice in the conduction band,the enhancement is so strong that signatures of correlated insulator appear,which may further develop into an energy gap depending on the correlation strength.At last,Fermi velocity derived from temperature coefficients of resistivity is compared between conduction and valence bands with different displacement fields.It is found that electronic correlation has a negative dependence on the Fermi velocity,which in turn could be used to quantify the correlation strength.

关 键 词：twisted multilayer graphene heterostructure correlated states van Hove singularity 

分 类 号：O469[理学—凝聚态物理] TQ127.11[理学—电子物理学]