Fe/NiO(100) and Fe/MgO(100) interfaces studied by X-ray absorption spectroscopy and non-linear Kerr effect

A structural characterization of the Fe/NiO(100) and Fe/MgO(100) interfaces is reported. Polarization-dependent X-ray absorption spectroscopy has been employed to explore the local atomic structure of the interfaces. A strong difference between the two systems is observed: the Fe/MgO(100) interface does not show a significant Fe oxidation or oxygen diffusion while a buckled Fe–O like layer is observed at Fe/NiO(001). Moreover, while on the MgO(001) substrate the tetragonal strain is released at 10 ML Fe thickness, a residual epitaxial strain can be observed on a film of the same thickness on NiO(001). A magnetic characterization of the Fe/NiO(001) system by linear and non-linear magneto-optical Kerr effect measurements is also reported and discussed.