Preparation and characterization of highly L21-ordered full-Heusler alloy Co2FeAl0.5Si0.5 thin films for spintronics device applications

We report the investigation of structure and magnetic properties of full-Heusler alloy Co2FeAl0.5Si0.5 (CFAS) thin films grown on MgO-buffered MgO (001) substrates through magnetron sputtering. It was found that single-crystal CFAS thin films with high degree of L2(1) ordering and sufficiently flat surface could be obtained after postdeposition annealing. All the films show a distinct uniaxial magnetic anisotropy with the easy axis of magnetization along the in-plane [110] direction. These results indicate that the use of the MgO buffer for CFAS is a promising approach for achieving a higher tunnel magnetoresistance ratio, and thus for spintronics device applications. (C) 2008 American Institute of Physics.