STANDING SPIN-WAVES OF AMORPHOUS CO-HF THIN-FILMS

Ferromagnetic resonance experiments were used to investigate the depen dence of surface magnetic properties on the film thickness, Hf concent ration, and annealing conditions for amorphous Co1-xHfx thin films dep osited on silicon substrate by DC magnetron sputtering method. The fil m thickness was varying between 1300 and 3000 Angstrom, and Hf concent ration was 16, 24, or 32 at.%. Annealing was carried out for various t imes at 150 degrees C and for various temperatures for one hour in the atmosphere. Measurements were carried out with the static magnetic fi eld perpendicular and parallel to the thin film plane at room temperat ure. When the static magnetic held was parallel to the film plane, onl y one peak(except for Co68Hf32) was observed in all films. However, wh en the static field was perpendicular to the film plane, subsidiary pe aks were observed in all films. These subsidiary peaks seperated into the volume standing spin-wave mode and the surface mode formed in the film surface by annealing at a low temperature (150 degrees C). The an nealing result shows that the surface mode can be explained by the str atification of Co concentration in the film and also suggests that the Co concentration changed with annealing time and temperature. We have quantitatively investigated the variations of the effective magnetiza tions in each layer for various annealing conditions by analyzing the surface mode with the dispersion relation of the uniform mode. Also, v olume standing spin-wave modes were analyzed in the surface pinning ap proximation.