Effect of magnon–LA phonon interaction on LA phonon excitation at finite temperature

Abstract

AbstractA magnon–longitudinal acoustic (LA) phonon interaction model is developed on the basis of a two‐dimensional square Heisenberg ferromagnetic system. The LA phonon excitation is studied by Matsubara–Green function theory, and the LA phonon excitation dispersion curves are calculated on the main symmetric lines in Brillouin zone (BZ). It is found that there exists obvious LA phonon hardening. The hardening of LA phonons becomes more evident near the M point of the BZ boundary. The influences of various parameters on LA phonon hardening are also discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)