Abstract
We have carried out an inelastic-neutron-scattering investigation of the high-temperature spin-wave excitations and the critical dynamics in the amorphous ferromagnet ( K). Well-defined spin-wave excitations are observed for wave vectors and for temperatures up to 555 K. The spin-wave dispersion relation over this range is well described by the expression , where meV and meV ; the power law appears to hold up to 450 K. Measurements at K show that the spin-wave damping is consistent with the Heisenberg-model prediction . In the critical region the spin-wave stiffness is found to follow the power law for , while at the energy width is consistent with for . These results are in satisfactory agreement with dynamical scaling theory for the Heisenberg ferromagnet and further they are in good accord with similar, albeit more-detailed, measurements in the crystalline transition metals Fe, Co, and Ni.
- Received 16 September 1977
DOI:https://doi.org/10.1103/PhysRevB.17.241
©1978 American Physical Society