Structure, magnetic properties and electrical resistivity of Co2FeSi1−xGax Heusler alloy thin films.

The influence of Ga on the structural, magnetic and half-metallic properties of Co 2 FeSi 1− x Ga x (0≤ x ≤1) thin films grown on Si (100) substrates using ultra high vacuum magnetron sputtering has been systematically investigated. The linear increase in cubic lattice parameter from 5.63 Å to 5.73 Å and the Curie temperature ( T C ) from 854 K to 941 K with x varying from 0 to 1 indicate the progressive substitution of Ga for Si. The coercivity ( H c ) was found to decrease from 26 Oe ( x =0) to 3 Oe ( x =1) at room temperature and is attributed to the decrease in magnetic anisotropy. The magnetic hysteresis loops measured from 300–873 K revealed that the film where Ga completely replaces Si exhibit better stability in both saturation magnetization ( M s ) and H c with temperature. The increase in coercivity at higher temperatures is attributed to the film to substrate interaction. The measured M s at 100 K decreases from 5.01 µ B /f.u. ( x =0) to 4.49 µ B /f.u. ( x =1) and follows the trend of Slater-Pauling rule. The indirect evidence of half-metallic nature is examined from the temperature dependent electrical resistivity measurements. [ABSTRACT FROM AUTHOR]