Accumulation and control of spin waves in magnonic dielectric microresonators by a comb of ultrashort laser pulses

TL;DR

This paper introduces a method to excite and control spin waves in magnetic microresonators using high-repetition-rate laser pulses, enabling tunable and switchable magnonic modes through nonthermal effects.

Contribution

It demonstrates a novel laser-based technique for tunable excitation and control of spin wave modes in magnetic microdisks via the inverse Faraday effect.

Findings

Resonant dependence of spin wave amplitude on external magnetic field.

Switching between volume and surface spin waves with small magnetic field variations.

High-repetition laser pulses induce interplay between spin wave resonances.

Abstract

Spin waves in magnetic microresonators are at the core of modern magnonics. Here we demonstrate a new method of tunable excitation of different spin wave modes in magnetic microdisks by using a train of laser pulses coming at a repetition rate higher than the decay rate of spin precession. The microdisks are etched in a transparent bismuth iron garnet film and the light pulses influence the spins nonthermally through the inverse Faraday effect. The high repetition rate of the laser stimulus of 10 GHz establishes an interplay between the spin wave resonances in the frequency and momentum domains. As a result, scanning of the focused laser spot near the disk boarder changes interference pattern of the magnons and leads to a resonant dependence of the spin wave amplitude on the external magnetic field. Apart from that, we achieved a switching between volume and surface spin waves by a small variation of the external magnetic field.