Acoustoelectric effects in quantum constrictions

TL;DR

This paper investigates how traveling acoustic waves induce a dc current in quantum constrictions, analyzing different frequency regimes and confirming findings with numerical calculations.

Contribution

It provides a detailed analysis of acoustoelectric effects in quantum constrictions, highlighting the roles of scattering and frequency regimes, supported by numerical simulations.

Findings

High-frequency regime explained by semi-classical models

Low-frequency acousto-conductance related to zero-field conductance

Numerical results confirm theoretical predictions for different constriction types

Abstract

A dc current induced in a quantum constriction by a traveling acoustic wave (or by non-equilibrium ballistic phonons) is considered. We show that in many important situations the effect is originated from acoustically-induced scattering between the propagating and reflecting states in the constriction. Two particular regimes corresponding to relatively high and low acoustic frequencies are discussed. In the first regime, the acoustoelectric effect in a smooth constriction can be understood by semi-classical considerations based on local conservation laws. For the low frequency regime, we show that the acousto-conductance is closely related to the zero field conductance. The qualitative considerations are confirmed by numerical calculations both for smooth and abrupt channels.