Spin-polarized tunneling is investigated in magnetic tunnel junctions containing an ultrathin interfacial layer of Co:TiO magnetic semiconductor. The Co:TiO layers (0 to 1 nm thick) are inserted at the SrTiO Co interface in La Sr MnO SrTiO Co tunnel junctions. For all junctions we find a negative tunnel magnetoresistance, which decreases upon the insertion of Co:TiO , while the junction resista...
