  The Photon Drag Effect (PDE) is a nonlinear process akin to optical
rectification in which the momentum of light is transferred to charged carriers
and converted to a DC voltage. Here, we experimentally demonstrate the
spin-polarized voltage, associated with the transference of light's spin
angular momenta to the linear momenta of charges, with visible-light
illumination on a nanovoid self-assembled plasmonic crystal surface. Numerical
calculations show that the gradient force, generally considered independent of
polarization, is responsible for the majority of the momentum transfer. The PDE
in this achiral system represents a distinct spin-orbit interaction that
produces asymmetric hotspots whose locations change with circular polarization
handedness. Our results significantly advance our understanding of the PDE and
demonstrate realistic potential for scalable plasmonic materials that utilize
PDE.
