Spin Wave Behavior in the Magnetization of an Amorphous Ferromagnet Gd₆₇Ni₃₃

Abstract

We have made precise measurements of the magnetization on an amorphous ferromagnet Gd₆₇Ni₃₃ below 300 K in fields up to 5.27 T. The magnetization obeys the simple spin wave T^3⁄2 law below about 90 K. The spin wave stiffness constant thus obtained is independent of magnetic fields and temperatures. The susceptibility follows the Curie-Weiss law above about 220 K. The amorphous Gd₆₇Ni₃₃ alloy is a typical example of Heisenberg ferromagnet such as amorphous Gd₆₈Cu₃₂ reported previously.