Asynchronous mass inversion enriched quantum anomalous Hall states in multilayer graphene

Abstract

Recently, multilayer graphene systems have attracted significant attention due to the discovery of a variety of intriguing phases, particularly quantum anomalous Hall (QAH) states. In rhombohedral pentalayer graphene (RPG), both QAH states with Chern number $C = -5$ and $C = -3$ have been observed. While the $C = -5$ QAH state is well understood, the origin of the $C = -3$ QAH state remains unclear. In this letter, we propose that the $C = -3$ QAH state, as well as the topological phase transition from $C = -3$ to $C = -5$ state in RPG, arises from an asynchronous mass inversion mechanism driven by the interplay between trigonal warping, staggered layer order, and the displacement field: Trigonal warping splits the low-energy bands of RPG into a central touching point and three satellite Dirac cones. Meanwhile, the coexistence of the staggered layer order and displacement field induces a momentum-dependent effective mass in the low-energy bands. Consequently, mass inversions at the central touching point and the satellite Dirac cones, induced by an increasing displacement field, can occur asynchronously, leading to the formation of the $C = -3$ QAH state and the topological phase transition from QAH state with $C=-3$ to $C=-5$. Additionally, based on this mechanism, we predict the presence of a $C=3$ QAH state in rhombohedral tetralayer graphene (RTG), which can be detected experimentally. Furthermore, this mechanism can also be applied to Bernal tetralayer graphene (BTG), explaining the origin of the observed $C=6$ QAH state.