Spin-polarized two-dimensional t(2g) electron gas: Ab initio study of EuO interface with oxygen-deficient SrTiO3

Using first-principles calculations we predict the existence of a spin-polarized two-dimensional electron gas (2DEG) at the interface of a ferromagnetic insulator EuO and oxygen-deficient SrTiO3. The carriers are generated by oxygen vacancies in SrTiO3 near the interface and have predominantly Ti-t(2g) orbital character. At the interface, the split-off d(xy)-derived conduction band of SrTiO3 is fully spin-polarized and the in-gap vacancy-induced state, found below the conduction-band edge, is aligned ferromagnetically with EuO. The calculations suggest a possible mechanism for generating spin-polarized 2DEG for spintronic applications.