Propagation of Acoustic Waves in Piezoelectric Media with a Subsonic Electric Current

Abstract

Sound propagation in a piezoelectric medium with a periodic lattice in the presence of charge carrier drift is considered. A periodic lattice creates a scattered component with wavenumbers equal to the sum and difference of the wavenumber of the initial sound wave $k$ and wavenumber of the periodic lattice $q$. The case $q \gg k$ when the lattice period is much smaller than the sound wavelength is considered. The phase velocity of the scattered components is much smaller than the phase velocity of sound. When interacting with charge carriers moving at a speed lower than the sound speed but higher than the propagation velocity of the scattered wave, the scattered component can take energy from the charge carriers. The possibility of primary sound amplification wave is demonstrated.