Magnetic property and interface structure of Ta/NiO/NiFe/Ta

Ta/NiO/NiFe/Ta multilayers, utilizing Ta as buffer layer, were prepared by rf reactive and de magnetron sputtering. The exchange coupling field betwee n NiO and NiFe reached a maximum value of 9.6x10(3) A/m at a NiO film thick ness of 50 nm. The composition and chemical states at interface region of T a/NiO/Ta were studied by using the X-ray photoelectron spectroscopy (XPS) a nd peak decomposition technique. The results show that there is an "intermi xing layer" at the Ta/NiO land NiO/Ta) interface due to a thermodynamically favorable reaction 2Ta + 5NiO = 5Ni + Ta2O5. This interface reaction has a great effect on exchange coupling. The thickness of Ni+NiO estimated by XP S depth. profiles is about 8-10 nm.