Interface stability in hybrid transition metal-oxide magnetic junctions

Recent experiments revealed an apparently bias-dependent tunneling magnetoresistance between a transition metal (such as Fe, Co) and an oxide barrier such as SrTiO3. We examine the materials issues involved in this type of hybrid transition metal-oxide junctions. The junction interface is shown to be unstable against thermal treatment or high-bias current stress. We conclude that the junction magnetoresistance is largely determined by the formation of an interface oxide layer different from the barrier or the transition metal electrode themselves.