Nuclear and Electronic Spin-Wave Relaxation Rates in the Hexagonal Antiferromagnet CsMnF3

Abstract

Nuclear and electronic spin-wave relaxation rates have been measured in the hexagonal antiferromagnet CsMnF3 in the flopped state using two kinds of parallel pumping experiments. In the first experiment, previously performed by Hinderks and Richards for RbMnF3, values of the product ηknηke are obtained from critical field data for simultaneous nuclear-electronic spin-wave instability using a 9.35 GHz pump. In the second experiment values of ηke are obtained by pumping at 17.5 GHz, twice the electronic spin-wave frequency. Reasonable agreement with a theory of Richards is obtained at 4.2° and 1.7°K for relaxation rates of the nuclear spin-waves having k ≈ 105 cm−1. For k ≈ 0 there is an order-of-magnitude discrepancy which may be accounted for if it is assumed that inhomogeneities strongly mix modes for k<105 cm−1. The electronic spin-wave linewidths for k ≈ 0 are much smaller than the AFMR which is independent of temperature from 4.2°–1.7°K. These results are consistent with a random strain-broadening interpretation of the AFMR width.