Ab initio study on interlayer exchange coupling in (Zn,Ni)O multilayers

Interlayer exchange coupling in (Zn, Ni)O multilayers is investigated by density functional theory calculations. We mainly study the effect of the nonmagnetic spacer and carrier in controlling the IEC between the magnetic layers separated by ZnO layers. It is found that, for the pure ZnO layers, the coupling between the two magnetic (Zn,Ni)O layers is always ferromagnetic, which is well interpreted by the RKKY interaction based on a gaped two-band model. However, the antiferromagnetic coupling is observed by N doping, which is in connection with the ZnO layers's thickness and the N atoms's sites. The p-d hybridization mechanism plays an important role in switching FM coupling to AFM coupling.