Light emitting diodes of inverse spin valves
  We propose making light emitting diodes out of inverse spin valves. The proposed diodes rely on the spin-dependent electron transport of inverse spin valves that are layered structures of a ferromagnetic half-metal sandwiched between two non-magnetic metals. Under a bias, a giant spin-dependent chemical potential difference between spin-up and spin-down electrons is created. Thus, the inverse spin valves are possible to emit light when electrons in higher chemical potential go to the lower chemical potential. The advantages of this type of light emitting diodes include tunableness and less demand on materials. 
X. R. Wang