Spin Blocker Using the Interband Rashba Effect in Symmetric Double Quantum Wells

Efficient generation of spins in nonmagnetic semiconductors is key to realizing all-electrical spintronic devices. The authors show that in symmetric double quantum wells of a narrow-gap semiconductor like (In,Ga)As, the interband Rashba effect provides an explicit mechanism for blocking only ``down'' spins (for example), in a parallel magnetic field that breaks time-reversal symmetry. Current-induced spin polarization should be enhanced dramatically in the proposed device, which is compatible with mature top-down fabrication techniques and thus offers a clear pathway to practical spintronics applications.