Tuning the magnetic anisotropy of Ga-rich FeGa thin films deposited on rigid substrates

Abstract We have investigated the possibility of growing on outward bent rigid substrates to create an in-plane magnetic anisotropy in Ga-rich FeGa layers grown in the diffusive flow that in principle are expected to be magnetically isotropic in the sample plane when using non-bent rigid substrates. In this work, samples were grown by sputtering in the diffusive regime in rigid outward bent substrates, i.e. substrates under tensile stress. After the growth of the layers, the release of the substrate promotes a compression in the sample plane confirmed by x-ray diffractometry. This compression strain induces a uniaxial magnetic anisotropy axis in the sample plane perpendicular to the mechanical stress as expected for a material with a positive magnetostriction. Moreover, a value of 73 ppm for the magnetostriction constant has been inferred from the magnetic anisotropy measurements in the as-grown layer. A thermal treatment at a moderate temperature of 300 °C partially release the strain, but it does not modify the magnetic anisotropy either in magnitude or direction.