Electronic and Magnetic Structures in Slab Models Including Al/Co and O/Co Interfaces

On the basis of the density-functional theory, we numerically calculated the interfacial magnetism of slab models including Al/Co and O/Co interfaces. We obtained the local magnetic moments and spin polarizations for various types of models. We found that the interfacial Al layers exhibit positive spin polarizaition in specific atomic arrangements, such as O/Al/Co. The sign is consistent with the experimental result of the ferromagnet/insulator/superconductor junction. This result suggests that in the junction Co/Al2O3/Co, the tunneling of s-character electrons in Al is favored to that of d-character electrons in Co.