# Polarization-Addressable Optical Movement of Plasmonic Nanoparticles and Hotspot Spin Vortices

## TL;DR

This paper explores how light polarization affects the movement of gold nanoparticles and the formation of spin vortices, offering new control in plasmonic and optical systems.

## Contribution

The study reveals how spin–orbit coupling in plasmonic systems leads to transverse spin and vortex formation, enabling polarization-controlled nanoparticle motion.

## Key findings

- Localized surface plasmon resonance induces transverse spin in gold monomers, altering nanoparticle trajectories based on polarization.
- Gold dimers exhibit vortex and anti-vortex spin pairs, influencing nanoparticle motion through resonant spin momentum distribution.

## Abstract

Spin–orbit coupling in nanoscale optical fields leads to the emergence of a nontrivial spin angular momentum component, transverse to the orbital momentum. In this study, we initially investigate how this spin–orbit coupling effect influences the dynamics in gold monomers. We observe that localized surface plasmon resonance induces self-generated transverse spin, affecting the trajectory of the nanoparticles as a function of the incident polarization. Furthermore, we investigate the spin–orbit coupling in gold dimers. The resonant spin momentum distribution is characterized by the unique formation of vortex and anti-vortex spin angular momentum pairs on opposite surfaces of the nanoparticles, also affecting the particle motion. These findings hold promise for various fields, particularly for the precision control in the development of plasmonic thrusters and the development of metasurfaces and other helicity-controlled system aspects. They offer a method for the development of novel systems and applications in the realm of spin optics.