Proximity-induced topological transition and strain-induced charge transfer in graphene/MoS2 bilayer heterostructures

TL;DR

This paper explores how proximity effects, strain, and twist in graphene/MoS2 heterostructures induce topological phase transitions, modify spin-orbit coupling, and enable charge transfer, revealing new quantum phases and electronic properties.

Contribution

It provides a comprehensive analysis of the electronic, spin, and topological properties of graphene/MoS2 heterostructures under various external influences, highlighting novel topological phases and strain-induced charge transfer mechanisms.

Findings

Proximity induces strong spin-orbit coupling in graphene.

Strain and twist significantly affect the electronic bandstructure.

Topological phase transition occurs under gate voltage.

Abstract

Graphene/MoS2 heterostructures are formed by combining the nanosheets of graphene and monolayer MoS2. The electronic features of both constituent monolayers are rather well-preserved in the resultant heterostructure due to the weak van der Waals interaction between the layers. However, the proximity of MoS2 induces strong spin orbit coupling effect of strength ~1 meV in graphene, which is nearly three orders of magnitude larger than the intrinsic spin orbit coupling of pristine graphene. This opens a bandgap in graphene and further causes anticrossings of the spin-nondegenerate bands near the Dirac point. Lattice incommensurate graphene/MoS2 heterostructure exhibits interesting moire' patterns which have been observed in experiments. The electronic bandstructure of heterostructure is very sensitive to biaxial strain and interlayer twist. Although the Dirac cone of graphene remains intact and no charge-transfer between graphene and MoS2 layers occurs at ambient conditions, a strain-induced charge-transfer can be realized in graphene/MoS2 heterostructure. Application of a gate voltage reveals the occurrence of a topological phase transition in graphene/MoS2 heterostructure. In this chapter, we discuss the crystal structure, interlayer effects, electronic structure, spin states, and effects due to strain and substrate proximity on the electronic properties of graphene/MoS2 heterostructure. We further present an overview of the distinct topological quantum phases of graphene/MoS2 heterostructure and review the recent advancements in this field.