Temperature dependence of the magnetic excitations in Gd

Abstract
We have made inelastic neutron scattering studies of the magnetic excitations in gadolinium above and below the Curie temperature (Tc = 293 K). The constant Q measurements were made out to the Brillouin zone boundaries in the [001] and [100] directions in the temperature range from 9 to 593 K. The small q spin‐wave energies renormalize in approximate proportionality to the net magnetization and approach zero at Tc. There is very little broadening of these peaks except at temperatures very near Tc. At large q, however, there is appreciable broadening but a much slower decrease of spin‐wave energies with increasing temperature. The large q peaks do not vanish at Tc; instead, they persist as broad shoulders in the magnetic excitation spectra up to about 1.2 Tc.