Topological Kondo insulator in MoTe2/WSe2 moiré bilayers

Abstract Topological Kondo insulators are a topologically protected insulating state induced by Kondo exchange interactions between itinerant electrons and local magnetic moments, as opposed to single-particle band inversion. They are characterized by an insulating bulk with Dirac surface states in three dimensions and helical edge states in two dimensions. Although experiments have supported the emergence of these insulators in the rare-earth compound SmB 6 , their observation in two-dimensional systems has not been demonstrated. Here we report the experimental evidence of a two-dimensional topological Kondo insulator in MoTe 2 /WSe 2 moiré bilayers. Using dual-gated devices, we prepare a triangular lattice of local moments in the MoTe 2 layer and a half-filled dispersive band in the WSe 2 layer with a chiral Kondo coupling. Using transport and compressibility measurements, we show that the state supports metallic transport at high temperature and an insulating bulk with helical edge conduction protected by spin- S z conservation at low temperature. Under high magnetic fields, the insulating state at low temperature becomes metallic. Our results demonstrate a highly tunable platform based on moiré materials for studying the interplay of strong interactions and topological order.