Moire-enabled topological superconductivity in twisted bilayer graphene

TL;DR

This paper proposes a method to induce topological superconductivity in twisted bilayer graphene using moire patterns, spin-orbit coupling, and exchange fields, tunable by doping, strain, and bias, without fine-tuning the twist angle.

Contribution

It introduces a new approach to realize topological superconductivity in twisted graphene layers without precise twist angle tuning, leveraging moire minibands and external fields.

Findings

Topological states with various Chern numbers can be achieved.

The method is effective for twist angles between 1.3 and 3 degrees.

Topological superconductivity can be realized without ultraflat dispersions.

Abstract

Twisted van der Waals materials have risen as highly tunable platform 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 moire 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 a fine tuning of the twist angle, but solely on the emergence of moire 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.