Spin-Wave Excitations in Ho0.5Er0.5

Abstract

The propagation of spin waves in the conical and spiral magnetic phases of the alloy Ho_0.5Er_0.5 has been studied by neutron inelastic scattering. The spin‐wave energies are comparable with those observed in Ho and Er. The spin‐wave dispersion curves at 4.2°K were analyzed in terms of the Fourier transformed exchange energy, J(q) ‐ J(0), and an effective anisotropy parameter. The linewidths and energies of certain spin‐wave modes were studied as a function of temperature. As the temperature was raised the spin‐wave energies decreased. The linewidth of the distribution at Q = (0, 0, 2π/c) increased sharply on raising the temperature toward the cone‐to‐spiral transition. No broadening was observed for the mode of the same wave vector in Ho over the same temperature range.