Magnon measurements on a γ-Mn 90Cu 10 single crystal

Abstract

Inelastic neutron scattering measurements of magnons in antiferromagnetic γ- Mn Cu (90% Mn) are reported for energy transfers up to 8 THz. The data are analysed in terms of a magnon dispersion relation ω q> = (C 2q 2+D 2) 1 2 that is heavily damped with wave vector dependent damping Γ( q) = Γ 0 + Γ 1 q. We estimate from our fits of the data that C = 39.8±0.7 THz Å and D = 2.3±0.1 THz, and compare these valueswith the results of other experiments. The linear dependence of the damping on wave vector is found to give a reasonable description of our data, in accordance with theoretical expectations.