Plasmonic generation of spin currents

TL;DR

This paper demonstrates that surface plasmons in metallic nanostructures can generate spin currents across interfaces, combining plasmonics with spintronics and opening new avenues for spin-based device development.

Contribution

It introduces the concept of plasmonic spin pumping, showing that surface plasmons can excite spin currents in a bilayer system, a novel integration of plasmonics and spintronics.

Findings

Spin currents are generated by surface plasmons in Au nanoparticles.

Surface-plasmon resonance condition enhances spin current generation.

Plasmonic spin pumping occurs via nonequilibrium spin states in the bilayer.

Abstract

Surface plasmons, free-electron collective oscillations in metallic nanostructures, provide abundant routes to manipulate light-electron interactions that can localize light energy and alter electromagnetic field distributions at subwavelength scales. The research field of plasmonics thus integrates nano-photonics with electronics. In contrast, electronics is also entering a new era of spintronics, where spin currents play a central role in driving devices. However, plasmonics and spin-current physics have so far been developed independently. Here, we demonstrate the generation of spin currents by surface plasmons. Using Au nanoparticles embedded in a Pt/BiY2Fe5O12 bilayer film, we show that, when the Au nanoparticles fulfill the surface-plasmon-resonance condition, spin currents are generated across the Pt/BiY2Fe5O12 interface. This plasmonic spin pumping results from nonequilibrium states of spins excited by surface-plasmon-induced evanescent electromagnetic fields in the BiY2Fe5O12 layer. Such plasmonic spin pumping will invigorate research on spin-current physics, and pave the way for future spin-based plasmonic devices.