Spin Wave Excitation in Amorphous Fe-P-C Alloys

The temperature dependence of the magnetization at low temperatures has been examined in order to obatin the information about the magnetic excitation in amorphous Fe-P-C ferromagnets. The result reveals clearly the T^<3/2> temperature dependence for the magnetization change, which is characteristic of low energy spin wave excitation with quadratic dispersion hω_q=D・q^2 for the wave vector q. The value of D for Fe_<80>P_<13>C_7 amorphous alloy is calculated to be 98 meV・A^2. The diminuation of the dispersion coefficient shows the increase of spin wave excitation in the amorphous state.