Morphology of the interfaces between transition metals and their native oxides: Role of interdiffusion processes

Abstract

The magnetic coupling phenomena appearing between a ferromagnetic transition metal and its antiferromagnetic oxide crucially depend on the composition and morphology of the interface. We present combined in-situ x-ray absorption spectroscopy and ex-situ x-ray reflectometry studies of the growth of a native-oxide layer and the interface formation with its metal parent. Two model systems, Fe and Ni, are investigated. It is found in the case of Fe that oxidation and reduction processes appear upon deposition of metal on the oxygen-rich oxide. This results in symmetric metal/oxide and oxide/metal interfaces. Comparison with the case of Ni, where no reduction is observed, shows that this symmetry is intrinsically linked to the underlying reduction process. These results have important consequences for the growth of transition-metal/oxide interfaces in general. © 2009 The American Physical Society.