Helicity current generation by distorted Rashba coupling

TL;DR

This paper presents a theoretical mechanism for generating helicity spin currents in Rashba systems through surface acoustic waves, offering new possibilities for spintronics without charge current involvement.

Contribution

It introduces a novel mechanism for direct spin-current generation from lattice distortion in Rashba systems, independent of charge currents or spin accumulation.

Findings

Helicity currents are generated by shear surface acoustic waves.

The generated currents are not aligned with lattice vorticity.

This mechanism differs from conventional spin-current generation methods.

Abstract

We theoretically study spin transport in two-or three-dimensional Rashba systems dynamically distorted by surface acoustic waves. The spin currents in the linear response to lattice distortion dynamics are calculated on the basis of a microscopic theory combined with local coordinate transformations. As a result, we find a mechanism of direct spin-current generation from lattice distortion not associated with a charge current or spin accumulation. Moreover, the in-plane helicity currents are generated by shear surface acoustic waves via the present mechanism. The generated helicity currents are not parallel to the vorticity of the lattice, and cannot be created with the conventional methods. Thus, our findings offer an alternative functionality of the conventional Rashba systems in the field of spintronics.