Surface plasmon-mediated nanoscale localization of laser-driven sub-THz spin dynamics in magnetic dielectrics

TL;DR

This paper demonstrates that surface plasmon-polaritons can localize and enhance laser-driven spin dynamics in magnetic dielectrics, enabling potential non-thermal, nanoscale magnetic recording techniques.

Contribution

It introduces a novel method for spatially confining and amplifying ultrafast spin precession using surface plasmon resonance in hybrid structures.

Findings

Achieved 0.41 THz localized spin precession.

Observed two orders of magnitude enhancement at surface plasmon resonance.

Demonstrated potential for nano-scale, non-thermal magnetic recording.

Abstract

Ultrafast all-optical control of spins with femtosecond laser pulses is one of the hot topics at the crossroads of photonics and magnetism with a direct impact on future magnetic recording. Unveiling light-assisted recording mechanisms for an increase of the bit density beyond the diffraction limit without excessive heating of the recording medium is an open challenge. Here we show that surface plasmon-polaritons in hybrid metal-dielectric structures can provide spatial confinement of the inverse Faraday effect, mediating the excitation of localized coherent spin precession with 0.41 THz frequency. We demonstrate a two orders of magnitude enhancement of the excitation efficiency at the surface plasmon resonance within the 100 nm layer in dielectric garnet. Our findings broaden the horizons of ultrafast spin-plasmonics and open pathways towards non-thermal opto-magnetic recording at the nano-scale.