Interactions and magnetism in graphene boundary states

TL;DR

This paper investigates how interactions influence the magnetic and electronic properties of boundary states in graphene, revealing spin polarization, charge correlations, and persistent currents depending on filling and interaction range.

Contribution

It provides a detailed analysis of interaction effects on graphene boundary states, highlighting phenomena like spin polarization, band dispersion, charge ordering, and current formation.

Findings

Boundary states become fully spin polarized near half filling.

Interactions induce finite dispersion in boundary state bands.

Charge correlations resemble Wigner crystal behavior away from half filling.

Abstract

We analyze interaction effects on boundary states of single layer graphene. Near a half filled band, both short and long-ranged interactions lead to a fully spin polarized configuration. In addition, the band of boundary states acquires a finite dispersion as function of the momentum parallel to the edge, induced by the interactions. Away from half filling the wavefunction develops charge correlations similar to those in a Wigner crystal, and the spin strongly alternates with the occupation of the boundary states. For certain fillings the ground state has a finite linear momentum, leading to the formation of persistent currents.