Acoustogalvanic Effect in Dirac and Weyl Semimetals

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid-State Physics

Background:

• The acoustoelectric effect, driven by sound-induced deformation potentials, is a known phenomenon in semimetals.
• Acoustic wave interactions in Dirac and Weyl semimetals can lead to novel physical effects.
• Pseudomagnetic fields in these materials are difficult to probe experimentally.

Purpose of the Study:

• To propose and theoretically investigate the acoustogalvanic effect as a new nonlinear mechanism for generating electric current.
• To differentiate the acoustogalvanic effect from the standard acoustoelectric effect.
• To explore the potential of the acoustogalvanic effect for probing dynamical deformations and pseudomagnetic fields in Dirac and Weyl semimetals.

Main Methods:

• Theoretical modeling of nonlinear response to acoustic waves in Dirac and Weyl semimetals.
• Analysis of current generation mechanisms, distinguishing between deformation potential and pseudomagnetic field contributions.
• Investigation of the scaling properties of the generated current with respect to material parameters like relaxation time.

Main Results:

• The acoustogalvanic effect is proposed as a nonlinear mechanism for direct current generation via acoustic waves in Dirac and Weyl semimetals.
• This effect originates from unscreened pseudomagnetic fields, unlike the screened electric fields in the acoustoelectric effect.
• The longitudinal acoustogalvanic current exhibits at least quadratic scaling with relaxation time, contrasting with the linear scaling of photogalvanic current.

Conclusions:

• The acoustogalvanic effect provides a novel pathway for generating electric current using acoustic waves in specific semimetal systems.
• Its unique origin in pseudomagnetic fields and distinct scaling properties make it distinguishable from other related effects.
• The effect is experimentally accessible and can serve as a valuable tool for investigating elusive dynamical deformations and pseudomagnetic fields in Weyl and Dirac semimetals.