Microstructure of Co2CrxFe1−xAl thin films for magneto-electronic applications

Thin films of the Heusler alloy Co2Cr0.6Fe0.4Al have been prepared by means of magnetron sputtering under varying conditions (sputter power, sputter pressure and substrate temperature). All the films are polycrystalline with the cubic B2 structure. The extent of Co-Al antisite defects, lattice constants, internal stress states are influenced by the sputter conditions which is related to differences in the saturation magnetization. The magnetic moment can be increased by additional annealing up to an optimum temperature of 400 °C, but does not reach the theoretically predicted value. Above 600 °C the metastable B2 phase transforms into either (ε)-Co/Cr or (α)-Co/Cr.