Optomagnets in nonmagnetic plasmonic nanostructures

TL;DR

This paper theoretically explores how plasmonic nanostructures can generate and confine static magnetic fields at the nanoscale through optically-induced DC currents driven by optical rectification and spin-orbit interactions.

Contribution

It introduces a hydrodynamic model to analyze optically-induced DC currents and magnetic fields in nonmagnetic plasmonic nanostructures, highlighting the role of metallic discontinuities.

Findings

Maximum static magnetic field at nanostructure corners

Magnetic fields are dramatically confined at nanoscale

Optical rectification drives the current loops

Abstract

Using a hydrodynamic model of the free electron gas of metal, we theoretically investigate optically-induced DC current loops in a plasmonic nanostructure. Such current loops originate from an optical rectification process relying on three electromotive forces, one of which arises from an optical spin-orbit interaction. The resulting static magnetic field is found to be maximum and dramatically confined at the corners of the plasmonic nanostructure, which reveals the ability of metallic discontinuities to concentrate and tailor static magnetic fields on the nanoscale.