Nuclear Relaxation in a Two-Dimensional Ferromagnet with Single-Ion Anisotropy: Application to the System Rb₂CrCl₄

Abstract

The nuclear spin-lattice and transverse relaxation times were calculated for a two-dimensional ferromagnet with single-ion anisotropy, using the renormalized spin-wave development. The experimental transverse relaxation rate of ⁵³Cr nuclei was fairly explained by the Suhl-Nakamura interactions and the two-magnon process. The calculated spin-lattice relaxation due to three-magnon process with exchange enhancement led to an unusual result: the enhancement factor is as high as 29.4 at 25 K i.e. much more than for an easy-axis ferromagnet and a three-dimensional one.