Emergence of Chern Insulating States in Non-Magic Angle Twisted Bilayer Graphene  

作　　者：Cheng Shen Jianghua Ying Le Liu Jianpeng Liu Na Li Shuopei Wang Jian Tang Yanchong Zhao Yanbang Chu Kenji Watanabe Takashi Taniguchi Rong Yang Dongxia Shi Fanming Qu Li Lu Wei Yang Guangyu Zhang 沈成;应江华;刘乐;刘健鹏;李娜;王硕培;汤建;赵岩翀;褚衍邦;Kenji Watanabe;Takashi Taniguchi;杨蓉;时东霞;屈凡明;吕力;杨威;张广宇(Beijing National Laboratory for Condensed Matter Physics,Key Laboratory for Nanoscale Physics and Devices,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;School of Physical Sciences,University of Chinese Academy of Sciences,Beijing 100190,China;School of Physical Sciences and Technology,ShanghaiTech University,Shanghai 200031,China;Shanghai Tech Laboratory for Topological Physics,ShanghaiTech University,Shanghai 200031,China;Beijing Key Laboratory for Nanomaterials and Nanodevices,Beijing 100190,China;Songshan-Lake Materials Laboratory,Dongguan 523808,China;Research Center for Functional Materials,National Institute for Materials Science,1-1 Namiki,Tsukuba 305-0044,Japan;International Center for Materials Nanoarchitectonics,National Institute for Materials Science,1-1 Namiki,Tsukuba 305-0044,Japan)

机构地区：[1]Beijing National Laboratory for Condensed Matter Physics,Key Laboratory for Nanoscale Physics and Devices,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China [2]School of Physical Sciences,University of Chinese Academy of Sciences,Beijing 100190,China [3]School of Physical Sciences and Technology,ShanghaiTech University,Shanghai 200031,China [4]Shanghai Tech Laboratory for Topological Physics,ShanghaiTech University,Shanghai 200031,China [5]Beijing Key Laboratory for Nanomaterials and Nanodevices,Beijing 100190,China [6]Songshan-Lake Materials Laboratory,Dongguan 523808,China [7]Research Center for Functional Materials,National Institute for Materials Science,1-1 Namiki,Tsukuba 305-0044,Japan [8]International Center for Materials Nanoarchitectonics,National Institute for Materials Science,1-1 Namiki,Tsukuba 305-0044,Japan

出　　处：《Chinese Physics Letters》2021年第4期96-102,共7页中国物理快报（英文版）

基　　金：National Key R&D program(Grant No.2020YFA0309604);the National Natural Science Foundation of China(Grant Nos.61888102,11834017,and 12074413);the Strategic Priority Research Program of CAS(Grant Nos.XDB30000000 and XDB33000000);the Key-Area Research and Development Program of Guangdong Province(Grant No.2020B0101340001);Research Program of Beijing Academy of Quantum Information Sciences(Grant No.Y18G11);the start-up grant of ShanghaiTech University;National Key R&D Program(Grant No.2020YFA0309601);Elemental Strategy Initiative conducted by the MEXT,Japan(Grant No.JPMXP0112101001);JSPS KAKENHI(Grant No.JP20H00354);CREST(JPMJCR15F3),JST。

摘　　要：Twisting two layers into a magic angle(MA) of ~1.1°is found essential to create low energy flat bands and the resulting correlated insulating,superconducting,and magnetic phases in twisted bilayer graphene(TBG).While most of previous works focus on revealing these emergent states in MA-TBG,a study of the twist angle dependence,which helps to map an evolution of these phases,is yet less explored.Here,we report a magnetotransport study on one non-magic angle TBG device,whose twist angle θ changes from 1.25° at one end to 1.43°at the other.For θ=1.25° we observe an emergence of topological insulating states at hole side with a sequence of Chern number |C|=4-|v|,where v is the number of electrons(holes) in moire unite cell.When θ> 1.25°,the Chern insulator from flat band disappears and evolves into fractal Hofstadter butterfly quantum Hall insulator where magnetic flux in one moire unite cell matters.Our observations will stimulate further theoretical and experimental investigations on the relationship between electron interactions and non-trivial band topology.

关 键 词：Angle MOIRE TWIST 

分 类 号：TQ127.11[化学工程—无机化工]