(a) Schematic illustration of light emitting process in . SU electrons near the Fermi level jump to the lower empty SD electronic states, and emit photons of well-defined polarity. (b) A sketch of a possible LED out of an inverse spin valve. If the magnetization of the half metal is along the z-axis, the light emitted by along the +z-direction will be right-hand circularly polarized. No light will emit in the xy-plane.