Gate-Tunable Exchange Coupling Between Cobalt Clusters on Graphene

TL;DR

This study uses ab initio calculations to show that electric fields can modulate exchange coupling between cobalt clusters on graphene, with potential for controllable magneto-electric effects.

Contribution

It demonstrates gate-dependent exchange interactions in cobalt-graphene systems, highlighting the importance of cluster registration for magnetic control.

Findings

Exchange coupling is strongly gate-dependent.

Sensitivity to sublattice registration affects magnetic interactions.

Potential for magneto-electric device applications.

Abstract

We use spin-density-functional theory (SDFT) ab initio calculations to theoretically explore the possibility of achieving useful gate control over exchange coupling between cobalt clusters placed on a graphene sheet. By applying an electric field across supercells we demonstrate that the exchange interaction is strongly dependent on gate voltage, but find that it is also sensitive to the relative sublattice registration of the cobalt clusters. We use our results to discuss strategies for achieving strong and reproducible magneto-electric effects in graphene/transition-metal hybrid systems.