A STUDY OF COMPLEX PERMEABILITY IN RARE EARTH-SUBSTITUTED COBALT NONMAGNETIC TRANSITION-METAL AMORPHOUS THIN-FILMS

By using radio-frequency (rf) sputtering, amorphous ferromagnetic thin films of composition (Co93Zr7)100-yREy (RE = Nd, Pr, Dy, Th, Gd, or S m: magnetic rare earth elements) have been prepared. This work was per formed for small amounts of RE substitution (y < 3). These exhibit sta tic soft magnetic properties similar to CoZr alloys. For all compositi ons studied, a low in-plane uniaxial anisotropy H(k) appears, whose ma gnitude depends upon composition and preparation parameters. Above a c ritical substitution level, a biaxial anisotropy exhibiting an in-plan e H(k) and a perpendicular component H(p) is measured for films contai ning Gd or Sm. The substitution by RE atoms essentially affects the fr equency-response shape of complex permeability, depending on nature, c oncentration of RE atoms and on values of both H(k) and H(p). High-fre quency permeability spectra could be well fitted by a theoretical mode l based on magnetization changes due to rotation, using a composition- dependent Landau-Lifshitz damping term. The results on films exhibitin g uniaxial or biaxial anisotropy are reported and discussed.