Magnetic anisotropy and magnetostrictive properties of sputtered Tb–Dy–Fe–Co thin films

Abstract

Tb–Dy–Fe–Co thin films grown on Si $$\left\langle {100} \right\rangle$$ substrates at different substrate temperatures viz., room temperature, 300, 400 and 500 °C were investigated for structural, microstructural, magnetic and magnetostrictive properties. Grazing incidence X-ray diffraction studies showed presence of amorphous structure for the as-deposited film. Structural studies further indicated formation of (Tb,Dy)2(Fe,Co)17 and Fe–Co phases for the films grown at higher substrate temperatures. Magnetization measurements displayed presence of strong in-plane magnetic anisotropy for all the films. In addition to this, formation of out-of-plane magnetic anisotropy co-existing with in-plane magnetic anisotropy was noticed for the films grown at higher substrate temperatures. Accordingly, magnetic force microscopy studies indicated a strong out-of-plane magnetic contrast for the films grown at higher substrate temperatures. The magnetostriction estimated from tip deflection measurement was found to be negligibly small for the film grown at intermediate temperature viz., 300 °C. However, with subsequent increase in substrate temperatures the magnetostriction was found to increase. The presence of strong out-of-plane magnetic anisotropy co-existing with in-plane components was found to be detrimental for the development of magnetostriction.