Quantum Goos-Hanchen effect in graphene

TL;DR

This paper explores the quantum Goos-Hanchen effect in graphene, revealing how it depends on pseudospin and affects conductance, with potential implications for electronic device design.

Contribution

It demonstrates the pseudospin-dependent sign change of the GH shift and its impact on mode degeneracy and conductance in graphene p-n interfaces.

Findings

Sign change of GH shift at a specific incident angle.

Doubling of mode degeneracy due to GH effect.

Stepwise conductance increase with channel width.

Abstract

The Goos-Hanchen (GH) effect is an interference effect on total internal reflection at an interface, resulting in a shift sigma of the reflected beam along the interface. We show that the GH effect at a p-n interface in graphene depends on the pseudospin (sublattice) degree of freedom of the massless Dirac fermions, and find a sign change of sigma at angle of incidence alpha*=arcsin[sin alpha_c]^1/2 determined by the critical angle alpha_c for total reflection. In an n-doped channel with p-doped boundaries the GH effect doubles the degeneracy of the lowest propagating mode, introducing a two-fold degeneracy on top of the usual spin and valley degeneracies. This can be observed as a stepwise increase by 8e^2/h of the conductance with increasing channel width.