Anisotropy induced by the bowed-substrate sputtering technique in positive/negative magnetostriction FeB/CoSiB bilayers

CoSiB and FeB single layers and CoSiB/FeB bilayers with thicknesses ranging from 250 to 1500 Å were grown on bowed glass substrates using rf sputtering. A magnetoelastic anisotropy was induced in the magnetic layers after removing the films from the sputtering chamber. The positive (FeB) and the negative (CoSiB) magnetostrictive single layers showed an easy magnetization axis transverse and parallel to the compression axis, respectively. The magnetic behavior of the CoSiB/FeB bilayers is shown to be extremely sensitive to the thickness of each layer, to their thickness ratios, and also to the deposition sequence of the layers on the substrate. These results are discussed in terms of the interactions between two magnetic phases with easy magnetization axes transverse to each other.