Exploring Proximity Coupling for Novel Spin-Dependent Phenomena

Abstract: In heterostructures made of two dissimilar materials, proximity coupling at the interface can have profound consequences on the physical properties of both. Numerous examples exist in condensed matter physics. I will present our recent work on proximity effects to induce spin-orbit coupling (SOC) and exchange interaction. In graphene/transition metal dichalcogenide (TMD) heterostructures, we have successfully induced up to 1.5 meV in Rashba SOC (two-three orders of magnitude greater than the intrinsic SOC strength) in graphene measured by quantum transport. To induce exchange interaction, we have exploited atomically flat rare-earth iron garnet films (e.g. yttrium iron garnet- YIG and thulium iron garnet- TIG) as the source of the exchange and demonstrated strong exchange interaction in graphene and the surface states of (Bi, Sb)2Te3 topological insulator. These two interactions are essential ingredients for realizing the quantum anomalous Hall state in both systems, which is very exciting for potential spintronic applications.