Resonant tunneling magnetoresistance in epitaxial metal-semiconductor   heterostructures
  We report on resonant tunneling magnetoresistance via localized states through a ZnSe semiconducting barrier which can reverse the sign of the effective spin polarization of tunneling electrons. Experiments performed on Fe/ZnSe/Fe planar junctions have shown that positive, negative or even its sign-reversible magnetoresistance can be obtained, depending on the bias voltage, the energy of localized states in the ZnSe barrier and spatial symmetry. The averaging of conduction over all localized states in a junction under resonant condition is strongly detrimental to the magnetoresistance. 
J. Varalda, A. J. A. de Oliveira, D. H. Mosca, J.-M. George, M.   Eddrief, M. Marangolo, V. H. Etgens