Spin-wave temperature dependence of gadolinium

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Abstract
Previous theoretical studies of the temperature dependence of the magnon dispersion curves of rare earth metals have usually considered only the renormalization due to spin‐wave interactions and the effect of temperature variations of the magnetocrystalline anisotropy. An important consideration which has not been included in these studies is the possible temperature dependence of the exchange coupling between the localized spins. Taking into account only the shorter conduction electron mean free path and the resulting decrease in the 4f‐4f coupling as T increases we can qualitatively understand the general features of the measured magnon dispersion curves. Our results are consistent with recent measurements on Gd alloys which relate the temperature dependence of the magnetic ordering temperature to the conduction electron mean free path.