Investigations of hybrid 2D semimetal heterostructures

Besides graphene, the only well studied 2D semimetal is WTe₂, which has strikingly different properties, including strong spin-orbit coupling, low symmetry, superconductivity and being a topological insulator in monolayers. We set out to investigate properties of hybrid combinations of these two semimetals, which could, for example, include strong induced spin-orbit coupling in the graphene or the modification of the superconductivity or excitonic pairing in the WTe₂. We have studied a series of hybrid devices constructed with both monolayer and bilayer graphene and WTe₂ and find charge transfer consistent with a work function difference. We analyze the effects on transport characteristics of upper and lower electrostatic gating, the application of magnetic fields, and we track the charge-neutral conditions for the constituent components and the sharing of charge between them. We identify emergent hybrid behavior that differs from that expected for a simple combination of the two materials in parallel.