Magneto-Attenuation of Sound in Semimetals: Longitudinal Waves

Abstract

The calculation of the magnetic field dependence of ultrasonic attenuation in a semimetal is discussed on a simple model of its band structure. The results are applied to the case where the electron and hole mean free paths are large compared to the wavelength of sound. A series of oscillations and a large peak in the attenuation as a function of magnetic field are derived. The oscillations are geometric resonances of the type previously derived for metals, and the large peak is associated with the presence of density waves in the electron-hole carrier gas. The theoretical results are discussed, compared with experimental data, and found to agree semiquantitatively with the latter.