Moving zero-gap Wannier-Mott excitons in graphene

TL;DR

This paper explores the theoretical existence of moving Wannier-Mott excitons in graphene, showing their energies depend on momentum and discussing potential experimental observation methods.

Contribution

It demonstrates the possibility of indirect moving excitons in graphene influenced by trigonal warping, with calculated binding energies and observation strategies.

Findings

Excitons depend on momentum and direction.

Binding energies vanish near conic points.

External electron scattering could observe these excitons.

Abstract

We demonstrate the possibility of existence of indirect moving Wannier-Mott excitons in graphene. Electron-hole binding is conditioned by the trigonal warping of conic energy spectrum. The binding energies are found for the lowest exciton states. These energies essentially depend on the value and direction of exciton momentum and vanish when the exciton momentum tends to the conic points. The ways to observe the exciton states are discussed. The opportunity of experimental observation of zero-gap excitons by means of external electron scattering is examined.