Acoustogalvanic effect in Dirac and Weyl semimetals

TL;DR

The paper introduces the acoustogalvanic effect, a nonlinear phenomenon in Dirac and Weyl semimetals where acoustic waves generate a direct current via pseudo-electromagnetic fields, offering a new way to probe these materials.

Contribution

It proposes the acoustogalvanic effect as a novel nonlinear mechanism for current generation in Weyl and Dirac semimetals, driven by pseudo-electromagnetic fields from acoustic waves.

Findings

The acoustogalvanic current scales quadratically with relaxation time.

The current depends on the direction of sound wave propagation.

The effect is within experimental reach for probing pseudo-fields.

Abstract

The acoustogalvanic effect is proposed as a nonlinear mechanism to generate a direct electric current by passing acoustic waves in Dirac and Weyl semimetals. Unlike the standard acoustoelectric effect, which relies on the sound-induced deformation potential and the corresponding electric field, the acoustogalvanic one originates from the pseudo-electromagnetic fields, which are not subject to screening. The longitudinal acoustogalvanic current scales at least quadratically with the relaxation time, which is in contrast to the photogalvanic current where the scaling is linear. Because of the interplay of pseudoelectric and pseudomagnetic fields, the current could show a nontrivial dependence on the direction of sound wave propagation. Being within the experimental reach, the effect can be utilized to probe dynamical deformations and corresponding pseudo-electromagnetic fields, which are yet to be experimentally observed in Weyl and Dirac semimetals.