Highly spin-polarized conducting state at the interface between nonmagnetic band insulators: LaAlO3/FeS2 (001).

First-principles density functional calculations demonstrate that a spin-polarized two-dimensional conducting state can be realized at the interface between two nonmagnetic band insulators. The (001) surface of the diamagnetic insulator FeS(2) (pyrite) supports a localized surface state deriving from Fe d orbitals near the conduction band minimum. The deposition of a few unit cells of the polar perovskite oxide LaAlO(3) leads to electron transfer into these surface bands, thereby creating a conducting interface. The occupation of these narrow bands leads to an exchange splitting between the spin subbands, yielding a highly spin-polarized conducting state distinct from the rest of the nonmagnetic, insulating bulk. Such an interface presents intriguing possibilities for spintronics applications.