Strong dependence of the magnetic anisotropy on the growth temperature of Fe3+xSi1-x (x=0.34) films on GaAs(1Â 1Â 3)A substrates

A strong dependence of the magnetic anisotropy on the growth temperature of Fe3+xSi1-x Heusler alloy films on GaAs(1 1 3)A substrates is reported for a composition of 17.5at.% Si (x=0.34). This composition of Fe-Si alloy lies within the stable phase of the technologically promising Heusler alloy Fe3Si. The layers grown at the optimized growth temperature of 250 °C exhibit the expected four-fold magnetic anisotropy, which arises from the magnetocrystalline anisotropy and the large demagnetization energy, similar to Fe films. However, an unexpected strong uniaxial magnetic anisotropy is found for samples grown at 200 and 400 °C with the easy axes along 〈332¯〉 and 〈1¯10〉, respectively. The uniaxial magnetic anisotropy of these samples are shown to be related to the inferior interface quality.