Spin-polarized two-dimensional electron gas at oxide interfaces.

The possibility of formation of a fully spin-polarized 2D electron gas at the SrMnO_3/(LaMnO_3)_1/SrMnO_3 heterostructure is predicted from density-functional calculations. The La(d) electrons become confined in the direction normal to the interface in the electrostatic potential well of the positively charged layer of La atoms, acting as electron donors. These electrons mediate a ferromagnetic alignment of the Mn t_2g spins near the interface via Zener double exchange and become, in turn, spin-polarized due to the internal magnetic fields of the Mn moments.