Using graphene to control magnetic anisotropy and interaction between supported clusters

Abstract

Stabilization of magnetic order in clusters/nanoparticles at elevated temperatures is a fundamentally challenging problem. The magnetic anisotropy energy (MAE) that prevents the thermal fluctuations of the magnetization direction can be around 1–10 K in free transition metal clusters of around a dozen atoms. Here we demonstrate that a graphene support can lead to an order of magnitude enhancement in the anisotropy of supported species. Our studies show that the MAE of supported Co _5 and Co _13 clusters on graphene increase by factors of 2.6 and 25, respectively. The enhancement is linked to the splitting of selected electronic orbitals that leads to the different orbital contributions along the easy and hard axis. The conductive support enables a magnetic interaction between the deposited species and the nature of the magnetic interaction can be controlled by the separation between supported clusters or by vacancies offering an unprecedented ability to tune characteristics of assemblies.

Keywords

• magnetic anisotropy
• transition metal clusters
• graphene
• density functional theory