Moiré-enabled topological superconductivity in twisted bilayer graphene

Abstract

Twisted van der Waals materials have risen as highly tunable platforms for realizing unconventional superconductivity. Here we demonstrate how a topological superconducting state can be driven in a twisted graphene multilayer at a twist angle of approximately 1.6 degrees proximitized to other 2D materials. We show that an encapsulated twisted bilayer subject to induced Rashba spin-orbit coupling, s-wave superconductivity, and exchange field generates a topological superconducting state enabled by the moir'e pattern. We demonstrate a variety of topological states with different Chern numbers highly tunable through doping, strain, and bias voltage. 
Our proposal does not depend on fine-tuning the twist angle, but solely on the emergence of moir'e minibands and is applicable for twist angles between 1.3 and 3 degrees. 
Our results establish the potential of twisted graphene bilayers to create artificial topological superconductivity without requiring ultraflat dispersions.