Electronic shells of Dirac fermions in graphene quantum rings in a magnetic field

TL;DR

This paper demonstrates the existence of degenerate electronic shells of Dirac fermions in graphene quantum rings and predicts how a magnetic field can remove degeneracy, leading to magnetic moments.

Contribution

It introduces a combined tight binding and configuration interaction approach to analyze electronic shells and magnetic properties in graphene quantum rings.

Findings

Degenerate electronic shells of Dirac fermions are present in narrow graphene rings.

Finite magnetic fields remove degeneracy of these shells.

Half-filled shells in graphene rings can produce finite magnetic moments.

Abstract

We present results of tight binding calculations demonstrating existence of degenerate electronic shells of Dirac Fermions in narrow, charge neutral graphene quantum rings. We predict removal of degeneracy with finite magnetic field. We show, using a combination of tight binding and configuration interaction methods, that by filling a graphene ring with additional electrons this carbon based structure with half-filled shell acquires a finite magnetic moment.