Acoustoelectric Effect in Metals

A classical Boltzmann theory is given of the acoustoelectric effect in monovalent metals, using Pippard's approach to the ultrasonic absorption by conduction electrons. Weinreich's phenomenological relation between the acoustoelectric effect and the ultrasonic absorption holds in all frequency ranges for both longitudinal and transverse ultrasonic waves. For longitudinal waves in the intermediate and high frequency ranges, the result is essentially identical with that derived from the quantum-mechanical calculation. The order of magnitude of the acoustoelectric effect in the low frequency range is smaller than Parmenter's result but larger than that obtained by Weinreich-Holstein's approach. A phenomenological theory is developed of the acoustoelectric effect due to electron transfer mechanism in polyvalent metals, the method of which can be applied also to many-valley semiconductors.