Spin-polarized tunneling is investigated in magnetic tunnel junctions containing an ultrathin interfacial layer of Co:TiO2 magnetic semiconductor. The Co:TiO2 layers (0 to 1 nm thick) are inserted at the SrTiO3/Co interface in La0.67Sr0.33MnO3/SrTiO3/Co tunnel junctions. For all junctions we find a negative tunnel magnetoresistance, which decreases upon the insertion of Co:TiO2, while the junction resistance increases strongly. This suggests that the ultrathin Co:TiO2 is a paramagnetic insulator that acts as an additional tunnel barrier, in contrast to thick (180 nm) layers grown under comparable conditions, which exhibit metallic impurity band conduction and room-temperature ferromagnetism.
- magnetic tunnel junction
- magnetic semiconductor
- Cobalt-doped TiO2
Lee, Y. J., Abhishek Kumar, A. K., Kumar, A., Vera Marun, I. J., de Jong, M. P., & Jansen, R. (2010). Magnetic tunnel junctions with Co:TiO2 magnetic semiconductor electrodes. IEEE transactions on magnetics, 46(6), 1683-1686. https://doi.org/10.1109/TMAG.2010.2046019