Скачать или смотреть Xiaoyu Wang - Theory of correlated Chern insulators in twisted bilayer graphene

Second talk of the Moore Foundation EPiQS Postdoctoral Seminar Series
October 18th, 2023

Abstract: Magic-angle twisted bilayer graphene is the best studied physical platform featuring moire potential induced narrow bands with non-trivial topology and strong electronic correlations. Despite their significance, the Chern insulating states observed at a finite magnetic field -- and extrapolating to a band filling, s, at zero field -- remain poorly understood. Here we report the first comprehensive study of interacting electrons in finite magnetic fields while varying the electron density, twist angle and heterostrain. Within a panoply of correlated Chern phases emerging at a range of twist angles, we uncover a unified description for the ubiquitous sequence of states with Chern number t for (s,t)=\pm (0,4), \pm(1,3),\pm(2,2) and \pm(3,1). In addition, we find correlated Chern insulators at unconventional sequences with fractional s, and elucidate their nature.