Gate-tunable magnetism of C adatoms on graphene

TL;DR

This study uses density functional theory to demonstrate that applying a gate voltage to graphene with carbon adatoms can precisely tune magnetic moments and magnetic coupling, offering a controllable magnetic property platform.

Contribution

It introduces a method to control magnetism in graphene via gate voltage, combining DFT calculations with Stoner and RKKY models for the first time.

Findings

Magnetic moments can be tuned from zero to 1μ_B with gate voltage.

Magnetic coupling switches between antiferromagnetism and ferromagnetism.

SCAN meta-GGA reduces magnetic moments and weakens ferromagnetism.

Abstract

We have performed density functional theory calculations of graphene decorated with carbon adatoms, which bind at the bridge site of a C--C bond. Earlier studies have shown that the C adatoms have magnetic moments and have suggested the possibility of ferromagnetism with high Curie temperature. Here we propose to use a gate voltage to fine tune the magnetic moments from zero to 1$\mu_B$ while changing the magnetic coupling from antiferromagnetism to ferromagnetism and again to antiferromagnetism. These results are rationalized within the Stoner and RKKY models. When the SCAN meta-GGA correction is used, the magnetic moments for zero gate voltage are reduced and the Stoner band ferromagnetism is slightly weakened in the ferromagnetic region.