Electrical Control of Exchange Bias Mediated by Graphene

The role of graphene in mediating the exchange interaction is theoretically investigated when it is placed between two ferromagnetic dielectric materials. The calculation based on a tight-binding model illustrates that the magnetic interactions at the interfaces affect not only the graphene band structure but also the thermodynamic potential of the system. This induces an indirect exchange interaction between the magnetic layers that can be considered in term of an effective exchange bias field. The analysis clearly indicates a strong dependence of the effective exchange bias on the properties of the mediating layer, revealing an effective mechanism of electrical control even at room temperature. This dependence also results in qualitatively different characteristics for the cases involving mono- and bilayer graphene.