Effect of a MgO interlayer on the structural and magnetic properties of Co₂Cr_0.6Fe_0.4Al thin films epitaxially grown on GaAs substrates

The effect of a MgO interlayer on the structural and magnetic properties of Co₂Cr_0.6Fe_0.4Al (CCFA) thin films epitaxially grown on GaAs substrates by sputtering was investigated. When the MgO interlayer thickness was 1.0 nm or less, the CCFA films were grown with a cube-on-cube relation to GaAs and no significant decrease in either the x-ray diffraction intensity or saturation magnetization was observed. In contrast, when the MgO thickness was 1.5 nm or more, the CCFA film was rotated by 45° in the (001) plane with respect to GaAs, and both the x-ray diffraction intensity and saturation magnetization decreased. All samples showed strong magnetic anisotropy, in which a uniaxial anisotropy with an easy axis of [110]_GaAs or [1-10]_GaAs dominated with a slight cubic anisotropy having an easy axis of <110>_CCFA superimposed.