Enhanced spin-precession dynamics in a spin-metamaterial coupled resonator observed in terahertz time-domain measurements

Abstract

We demonstrate enhancement of the spin precession of orthoferrite ${\mathrm{ErFeO}}_{3}$ using the magnetic near-field produced by a split-ring resonator (SRR), using the terahertz pump-optical Faraday probe measurement. The precession amplitude was enhanced by \ensuremath{\sim}8 times when the resonance frequency of spin precession was close to the magnetic resonance of SRR. The time evolution of spin precession was successfully reproduced by a coupled spin- and SRR-resonance model mediated by the magnetic near-field. It is suggested that optimization of the metamaterial structure would further increase the enhancement factor, leading to the nonlinear control of spin dynamics using terahertz radiation.