Magnetic Phases of Graphene Nanoribbons under Potential Fluctuations

TL;DR

This study explores how potential fluctuations and electron interactions influence the magnetic phases of graphene nanoribbons, revealing a transition from antiferromagnetic to ferromagnetic states under strong disorder.

Contribution

It demonstrates that electron-electron interactions stabilize edge states against potential fluctuations and identifies a disorder-induced magnetic phase transition.

Findings

Edge states are robust against potential fluctuations due to electron-electron interactions.

Strong disorder causes a transition from antiferromagnetic to ferromagnetic edge coupling.

Results align with recent experimental observations.

Abstract

We investigate the effects of long-range potential fluctuations and electron-electron interactions on electronic and magnetic properties of graphene nanoribbons with zigzag edges using an extended mean-field Hubbard model. We show that electron-electron interactions make the edge states robust against potential fluctuations. When the disorder is strong enough, the presence of electron-hole puddles induces a magnetic phase transition from antiferromagnetically coupled edge states to ferromagnetic coupling, in agreement with recent experimental results.