MAGNETIC FIELD EFFECT ON SOUND VELOCITY AND ATTENUATION IN AN ITINERANT ELECTRON FERROMAGNET

Abstract

In this paper we present the result of a systematic numerical calculation on the temperature dependence of magnetic field effects on the velocity and attenuation constant of longitudinal acoustic sound for both T<Tc and T>Tc of an itinerant electron ferromagnet. Attributing the origin of these magnetic field effects to the change in the screening of the ion-ion interaction which is caused by a magnetic field, first we reformulate this problem in a unified way. Then we make numerical calculation with a simple model electronic density of states and see how sensitively the sign, size, and temperature variation of these magnetic field effects depend on the details of electronic structure and electron interaction. We find that these magnetic field effects can be very strongly exchange enhanced. These findings suggest the possibility of using such magnetic field effects as a probe of the electronic structure and electron interaction in an itinerant electron ferromagnet. Finally we point out that by measuring the magnetic field effect on sound velocity we can infer the effect of the electron-phonon interaction on the magnetic properties.