Exchange coupling between NiO and NiFe thin films

NiO/NiFe bilayer thin films were prepared by rf reactive and dc magnetron sputtering, respectively. The exchange coupling strength between NiO and NiFe as a function of NiO texture and interface roughness was investigated by using different sputtering pressures, Au, and Cu buffer layers. The experimental results show that the exchange coupling field strongly depends on the NiO/NiFe interface roughness. In addition, we found the exchange coupling is largest for the (200) texture compared to the (111)-texture films. This is surprising since the bulk spin structure of NiO predicts the (200) plane to be compensated while the (111) plane is to be uncompensated.