2025/02/18 by Feng, Xilin, Sun, Zi-Ting, Law, K. T.
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Strongly Correlated Electrons (cond-mat.str-el)
paper · doi:10.48550/arxiv.2502.13229
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.