Spin wave relaxation processes in calcium-vanadium-iron garnet

The spin-wave dissipation parameter 2ΔHsub(k) of a calcium-vanadium-iron garnet (CVIG) single crystal was determined by the longitudinal pumping method at 35.5 GHz. The influence of ''impurity''iron ions of valence other than main became considerable at moderately low temperatures (approximately 250-3000K). This influence resulted in the increase of 2ΔKsub(k→0) when the temperature was lowered. In contrast to yttrium iron garnet, the k-dependent component of 2ΔHsub(k) of CVIG was considerably greater than the theoretical sum of the contributions of the three- and four-magnon processes. The difference, which could also be explained by the contribution of rapidly relaxing iron ions, depended linearly on k in the range k greater than or approximately 2 x 105cm-1 and the slope of this dependence increased when the temperature was lowered