Aluminum thickness dependence of resistance change in spin tunneling junctions Co/Al-oxide/Co

The oxidation states of Al-oxide layer and the leakage current density in coercive differential spin tunneling junctions Co/Al-oxide/Co have been investigated in order to clear the mechanism of the increasing resistance change. X-ray photoelectron spectroscopy analysis shows that the resistance change increases with decreasing unoxidized Al, which can be qualitatively explained by using first-principle band calculation based on linear-muffin-tin-orbital atomic-sphere-approximation method. The resistance change decreases with increasing leakage current density, which originates from Schottky effect. Reduction of unoxidized Al and leakage current density originating from Schottky effect is required to obtain the large resistance change in spin tunneling junctions.