Anomalous Interaction Dependence in Magnetism of Graphene Nanoribbons with Zigzag Edges

TL;DR

This study investigates the magnetic properties of zigzag-edged graphene nanoribbons, revealing anomalous power-law dependencies of magnetic moments and critical temperature on the on-site repulsion, influenced by ribbon width and localized electronic states.

Contribution

It uncovers anomalous interaction dependence in the magnetism of graphene nanoribbons, highlighting the role of localized states and ribbon width in magnetic behavior.

Findings

Magnetic moments depend on the on-site repulsion with a power-law relation.

Critical temperature shows similar anomalous power-law dependence.

Dependences are influenced by the width of the nanoribbons.

Abstract

Properties in magnetic ordered states of graphene nanoribbons with zigzag shaped edges are investigated by applying mean-field approximation to the Hubbard model with on-site repulsion $U$. We observe that magnetic moments and critical temperature show anomalous power-law dependences as a function of $U$; the actual values of the power are determined by only the width of ribbons. Such singular behaviours are found to be due to localized nature of the electronic states close to Fermi energy.