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Layer-engineered quantum anomalous Hall effect in twisted rhombohedral graphene
Zhangyuan Chen1,2, Naitian Liu1,2, Jiannan Hua1,2
1Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science, Westlake University, Hangzhou, China.
Abstract:
Realizing programmable topological states in quantum anomalous Hall (QAH) insulators requires tuning their topological invariant, the Chern number C. Here we report a QAH platform based on twisted rhombohedral graphene, in which C becomes a programmable and electrically tunable degree of freedom. In twisted monolayer-multilayer (1 + N) rhombohedral graphene, we find QAH states with C = N, where the layer number N = 3, 4, 5 directly sets the Chern number. We further demonstrate in situ electrical control. In a twisted monolayer-trilayer device, the sign of C is switched by electrostatic doping or displacement field. In addition, in twisted Bernal bilayer-rhombohedral tetralayer graphene, we drive a displacement-field-induced topological phase transition between two distinct QAH states with C = 3 and C = 4. Our work establishes a layer-engineered and electrically tunable platform that could lead to the on-demand engineering of correlated topological states.
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