Spin and electronic correlations in gated graphene quantum rings

TL;DR

This paper develops a theoretical model for gated graphene quantum rings, predicting how electron interactions and size influence the system's ground state and spin polarization.

Contribution

It introduces a combined tight-binding and configuration interaction approach to analyze spin states in graphene quantum rings, highlighting size-dependent effects.

Findings

Ground state spin varies with shell filling and system size.

Maximum spin polarization occurs after a critical ring size.

Size influences the spin polarization at half filling.

Abstract

We present a theory of graphene quantum rings designed to produce degenerate shells of single particle states close to the Fermi level. We show that populating these shells with carriers using a gate leads to correlated ground states with finite total electronic spin. Using a combination of tight-binding and configuration interaction methods we predict ground state and total spin of the system as a function of the filling of the shell. We show that for smaller quantum rings, the spin polarization of the ground state at half filling depends strongly on the size of the system, but reaches a maximum value after reaching a critical size.