Stacking order, interaction and weak surface magnetism in layered graphene sheets

TL;DR

This paper uses a Hubbard model to explain how stacking order in layered graphene influences its electronic properties, revealing that rhombohedral stacking can become a weak surface antiferromagnetic insulator.

Contribution

It introduces a Hubbard model that accounts for stacking-dependent electronic phases in layered graphene, explaining experimental observations.

Findings

Rhombohedral stacking leads to an insulating phase with weak surface antiferromagnetism.

Bernal stacking remains metallic despite interactions.

The model aligns well with recent transport experiment results.

Abstract

Recent transport experiments have demonstrated that the rhombohedral stacking trilayer graphene is an insulator with an intrinsic gap of 6meV and the Bernal stacking trilayer one is a metal. We propose a Hubbard model with a moderate $U$ for layered graphene sheets, and show that the model well explains the experiments of the stacking dependent energy gap. The on-site Coulomb repulsion drives the metallic phase of the non-interacting system to a weak surface antiferromagnetic insulator for the rhombohedral stacking layers, but does not alter the metallic phase for the Bernal stacking layers.