Dispersion in Ferromagnets Interacting with Phonons

Abstract

AbstractConsidering the magnon‐phonon interaction it is found that there is a net reduction of Heisenberg exchange. The reduction is maximum for the magnon wave vector given by K0 = v/(2cD) where v is the sound velocity and D is just 2SJa with a0 as the lattice constant. Thus the reduction is found to depend inversely on the exchange itself. There is also a new analog of Kohn like discontinuity occuring at the magnon wave vector k8 = ½ (qm + v/cD) with qm as the maximum wave vector of the phonons. In consideration of thermal magnon scattering a kink in the magnon dispersion is thus predicted at ks. The approximate temperature dependence arising in the exchange from the magnon‐phonon coupling is discussed.