Spin waves in an amorphous metallic ferromagnet

Low angle inelastic neutron scattering experiments have been carried out on the amorphous ferrromagnet Fe 75P 15C 10, with a Curie temperature Tc=597 °K. At reduced temperatures, t=T/Tc, between 0.5 and 0.83 well‐defined spin waves have been observed with propagation vectors ‖q‖=2π/γ<0.18 A−1 with a ferroamgnetic dispersion relation h/ω=D(T)q2+E(T)q4. Inability to close the scattering triangle rather than intrinsic broadening prevents extension of the measurements to even shorter wavelengths. At room temperature D=149.5(±3)meV−A2 and E=680(±200) meV−A4.