Coverage-dependent magnetic and electronic properties of graphene with Co adatoms

TL;DR

This study investigates how varying Co adatom coverage on graphene affects its magnetic and electronic properties, revealing coverage-dependent aggregation, hybridization effects, and potential topological states like the quantum anomalous Hall effect.

Contribution

It provides a systematic first-principles analysis of coverage-dependent magnetic and electronic behaviors of Co-decorated graphene, highlighting the formation of bilayer systems and topological states.

Findings

Co coverage > 1/3 ML leads to Co monolayer formation and bilayer systems.

Co adatoms are spin polarized with moments of 1.1 to 1.4 μB at lower coverage.

Hybridization induces new bands and potential quantum anomalous Hall states.

Abstract

Decorating two-dimensional materials with transition-metal adatoms is an effective way to bring about new physical properties that are intriguing for applications in electronics and spintronics devices. Here, we systematically studied the coverage-dependent magnetic and electronic properties of graphene decorated by Co adatoms, based on first-principles calculations. We found that the if the Co coverage is larger than 1/3 ML, the Co atoms will aggregate to form a Co monolayer and then a van der Waals bilayer system between the Co monolayer and graphene forms. When the Co coverage is <= 1/3 ML, the Co adatom is spin polarized with spin moment varying from 1.1 ~ 1.4 {\mu}B. The d(xz/yz) and d(xy/x2-y2 ) orbitals of Co hybridize significantly with the {\pi} bands of graphene, which generates a series of new bands in the energy range from -2 eV to 1 eV with respect to Dirac point of graphene. In most cases, the new bands near the Fermi level lead to topological states characterized by the quantum anomalous Hall effect.