Structural and magnetic effects induced by annealing in sputtered thin films of R1-XCoX amorphous alloys

Abstract

The objective of this work was to study the thermo-magnetic properties of sputtered R1-xCox amorphous alloys (R= Er, Tb, Sm). We have investigated a series of amorphous thin film of R1-xCox having a high Curie temperature Tc (above room temperature), which rises with Co content. The desired parameters were Tc higher than in crystalline state and low macroscopic anisotropy. Samples of R1-xCox have been prepared by DC triode sputtering from different targets. All of them have been then examined by means of X-ray diffraction for determining the as-cast amorphous structure and after each step of annealing, Rutherford back scattering (RBS) for determining the thickness and chemical composition. Magnetic measurements were taken before and after annealing (up to 400°C) at room temperature by means of vibrating sample magnetometer (VSM). These alloys were initially magnetically hard and characterized by a biaxial anisotropy in the film plane. Field annealing allowed to get both desired effects: first, reduction of internal stresses which were caused by the deposition process; second, producing a well-defined in plane anisotropy.