  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.
