Atomic and electronic structure ofCo/SrTiO3/Comagnetic tunnel junctions

Abstract

First-principles density-functional calculations of the atomic and electronic structure of ${\mathrm{C}\mathrm{o}/\mathrm{S}\mathrm{r}\mathrm{T}\mathrm{i}\mathrm{O}}_{3}/\mathrm{Co}$ (001) magnetic tunnel junctions (MTJ's) are performed. Different interface terminations are considered and the most stable structure with the ${\mathrm{TiO}}_{2}$ termination is identified based on energetics of adhesion. The calculated electronic structure of the ${\mathrm{TiO}}_{2}$-terminated MTJ shows an exchange coupling between the interface Co and Ti atoms mediated by oxygen. This coupling induces a magnetic moment of $0.25{\ensuremath{\mu}}_{B}$ on the interface Ti atom, which is aligned antiparallel to the magnetic moment of the Co layer. We argue that this might cause an inversion of the spin polarization of tunneling across the ${\mathrm{SrTiO}}_{3}$ barrier which was found in recent experiments.