Proximity induced topological state in graphene

TL;DR

This paper demonstrates that a topological phase can be induced in graphene through proximity to the topological insulator Bi$_2$Se$_3$, resulting in a hybrid state with topologically protected properties.

Contribution

It shows that proximity effects can transfer topological phases from Bi$_2$Se$_3$ to graphene, creating a new topologically protected state at their interface.

Findings

A hybrid state forms at the graphene/Bi$_2$Se$_3$ interface.

The hybrid state exhibits Dirac-cone-like dispersion.

The state has a helical spin-texture indicating topological protection.

Abstract

The appearance of topologically protected states at the surface of an ordinary insulator is a rare occurrence and to date only a handful of materials are known for having this property. An intriguing question concerns the possibility of forming topologically protected interfaces between different materials. Here we propose that a topological phase can be transferred to graphene by proximity with the three-dimensional topological insulator Bi$_2$Se$_3$. By using density functional and transport theory we prove that, at the verge of the chemical bond formation, a hybrid state forms at the graphene/Bi$_2$Se$_3$ interface. The state has Dirac-cone-like dispersion at the $\Gamma$ point and a well-defined helical spin-texture, indicating its topologically protected nature. This demonstrates that proximity can transfer the topological phase from Bi$_2$Se$_3$ to graphene.