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

Alexander Chekhov, Alexander I. Stognij, T. Satoh, Tatiana V. Murzina, I. Razdolski, Andrzej Stupakiewicz,

https://pubs.acs.org/doi/abs/10.1021/acs.nanolett.8b00416?journalCode=nalefd

We report spatial localization of the effective magnetic field generated via the inverse Faraday effect employing surface plasmon polaritons (SPPs) at a hybrid Au/rare-earth iron garnet interface. Analyzing, both numerically and analytically, the electric field of the SPPs at a hybrid interface, we corroborate our study with a proof-of-concept experiment showing efficient SPP-driven excitation of coherent spin precession with a 0.41 THz frequency. We argue that the sub-diffractional confinement of the SPP electric field enables strong spatial localization of the SPP-mediated excitation of spin dynamics. We demonstrate a two orders of magnitude enhancement of the excitation efficiency at the surface plasmon resonance within a 100 nm layer of a dielectric garnet. Our findings broaden the horizons of ultrafast spin-plasmonics and open pathways towards non-thermal opto-magnetic recording on the nanoscale.