Role of interface in ferromagnetism of (Zn,Co)O films

We demonstrate that room temperature ferromagnetic response (RT FR) of ZnCoO films grown at low temperature by the atomic layer deposition (ALD) method is due to Co metal accumulations at the ZnCoO/substrate interface region. The accumulated experimental evidences allow us to reject several other explanations of this effect in our samples, despite the fact that some of them are likely to be responsible for the low temperature FM in this class of the material.