Magnetic properties of epitaxial Co/sub 2/Cr/sub 1-x/Fe/sub x/Al full Heusler alloy thin films with the L2/sub 1/ structure

Co/sub 2/Cr/sub 1-x/Fe/sub x/Al full Heusler alloy thin films (x/spl ges/0.4) have been epitaxially grown on GaAs(001) substrates under the optimized condition. Structural analysis reveals the detailed growth mechanism of the films and confirms that the films form the perfectly ordered L2/sub 1/ structure. A magnetization measurement also shows the films possess very strong uniaxial crystalline anisotropy due to the epitaxial growth. By using these films as bottom electrodes of magnetic tunnel junctions, the maximum tunnel magnetoresistance ratio of 8.8% is observed after post-annealing with Al-O insulating barriers for x=1.