Easy axis and easy plane magnetization in D.C. sputtered amorphous YCo3 films

Abstract

The presence of a transient layer growth of about 500 Å thick in D.C. sputtered amorphous YCo₃ films has been detected by a study in the range 4–300 K of ferromagnetic resonance in films of thickness in the range 0.05 to 1.0 μm. The surface mode observed in films e≳0.2 μ transforms into the uniform one for e=0.05 μ. A model of exchange coupled layers explain the results observed. From relaxation process and Bloch law dependence of 4πM_S, it is seen that cobalt in the transient layer at the substrate film interface could have an ionic character and in the rest of the film a metallic one. We propose that the transient layer might have a higher Ar content leading to a strong in plane anisotropy. This was verified by subjecting films to an annealing at 200 °C for 24 h in pure Ar atmosphere which indeed induces a very strong in plane anisotropy K_U=−5.10⁵ ergs cm⁻³ at 300 K irrespective of film thickness. This in our opinion is the first direct demonstration of the effect of Ar to induce K_U<0.