Flat-band ferromagnetism in armchair graphene nanoribbons

TL;DR

This paper investigates flat-band ferromagnetism in armchair graphene nanoribbons, revealing a novel magnetic state caused by quantum interference effects and proposing experimental realization methods.

Contribution

It introduces a new type of flat-band ferromagnetism in armchair graphene nanoribbons using effective field theory and variational methods.

Findings

Identification of a new flat-band ferromagnetic ground state

Quantum interference leads to quenched kinetic energy at specific doping

Discussion on experimental realization of the magnetic state

Abstract

We study the electronic correlation effects in armchair graphene nanoribbons that have been recently proposed to be the building blocks of spin qubits. The armchair edges give rise to peculiar quantum interferences and lead to quenched kinetic energy of the itinerant carriers at appropriate doping level. This is a beautiful one-dimensional analogy of the Landau-level formation in two dimensions except the magnetic field is not needed here. Combining the techniques of effective field theory and variational wave function approach, we found that the ground state exhibits a new type of flat-band ferromagnetism that hasn't been found before. At the end, we address practical issues about realization of this novel magnetic state in experiments.