Magnetic semiconductors based on cobalt substituted ZnO

We have investigated the microstructure and the magnetic properties of cobalt substituted ZnO thin films deposited on sapphire (0001) substrates by pulsed laser deposition. We have optimized the growth condition using in situ monitoring by reflection high-energy electron diffraction. We found that ferromagnetic films need to be grown at low oxygen partial pressure (<10−6 Torr). Films with 25% of Co are ferromagnetic at room temperature with clear out-of-plane anisotropy. We have looked for spurious origins of the ferromagnetic signal and found none.