Strain induced topological transitions in twisted double bilayer graphene  

作　　者：Guoyu Luo Xinyu Lv Lu Wen Zhiqiang Li Zhenbing Dai 

机构地区：[1]College of Physics,Sichuan University,Chengdu 610064,China [2]Department of Physics,Sichuan Normal University,Chengdu 610066,China

出　　处：《Frontiers of physics》2022年第2期89-97,共9页物理学前沿（英文版）

基　　金：the National Natural Science Foundation of China for the support(Grant No.11874271).

摘　　要：We theoretically study the band structures and the valley Chern numbers of the AB-AB and AB-BA stacked twisted double bilayer graphene under heterostrain effect.In the absence of heterostrain,due to the constrains by the spatial symmetries,the central two flat bands of the AB-AB are topological trivial bands,while in the AB-BA they have a finite Chern number.The heterostrain breaks all the point group symmetries and the constrains are lifted,hence the topological properties of the two arrangements can be tuned by different strain magnitudesεand directionsφ.The heterostrain has dissimilar impacts on the Chern numbers of the AB-AB and AB-BA,owing to their different band gaps,and these gaps can be modified by a vertical electric field.Our results show that the topological transitions for both arrangements occur in theεrange of 0.1%-0.4%,which can be realized in the graphene-based sample.

关 键 词：valley Chern number twisted double bilayer graphene flat bands heterostrain 

分 类 号：O18[理学—数学]