Eur. Phys. J. B 4, 179-184 (1998)
https://doi.org/10.1007/s100510050367

New aspects of critical sound attenuation in magnetic systems with spin-lattice relaxation

Institute of Physics, A. Mickiewicz University, Poznań, Poland

Corresponding author: ^a pawlak@phys.amu.edu.pl

Received: 9 December 1997
Accepted: 24 February 1998
Published online: 15 July 1998

Abstract

A general theory of critical sound propagation, including phonon-spin-energy coupling, is studied in anisotropic magnets above their transition temperature. The Kawasaki weak singularity in the ultrasonic attenuation is found as a nonasymptotic effect. A new nonasymptotic regime similar to the one in the binary mixture is also determined. The role of coupling constants and the bare relaxation times in establishing the dominance region of particular terms, is discussed.