Optoelectronic phenomena in gold metal nanostructures due to the inverse Faraday effect

The inverse Faraday effect (IFE) is an opto-magnetic phenomenon that produces static magnetic fields in a wide range of materials during illumination with circularly polarized light. This study analyzes non-magnetic gold (Au) metal nanostructures, providing insight into plasmonic enhancement of the magnetic and optoelectronic phenomena associated with the IFE. We report a simple numerical approach in combination with full-wave optical simulations (finite-difference time-domain method) for tracking the optically-induced motion of electrons inside plasmonic nanostructures that gives rise to the IFE. In addition to static magnetic fields, a circulating drift current is observed, where the direction of current is the same as the chirality of the circularly polarized light. Our results indicate a significant enhancement of this drift current by ~100 times in Au nanoparticles due to larger optical field gradients in comparison with bulk Au films. We also report on the size, geometry, and spectral dependence of the induced drift currents and static magnetic fields, which we predict can exceed 1×10^-3 T under 10¹⁵ W m^-2 optical intensity for spherical Au nanoparticles. Our results inform the development of new classes of magneto-optic and optoelectronic behavior that can be obtained via direct manipulation of electron dynamics by the optical fields inside metals.