Picosecond acoustic excitation driven ultrafast magnetization dynamics in dielectric Bi-substituted yttrium iron garnet

TL;DR

This study demonstrates that picosecond acoustic pulses generated by femtosecond optical excitation can induce coherent magnetization precession in dielectric Bi-YIG films, revealing a new method for ultrafast magnetic control.

Contribution

It introduces a novel approach to control magnetization in dielectric garnets using strain pulses generated by optical excitation, expanding the understanding of magnetoelastic effects in complex heterostructures.

Findings

Strain pulses induce coherent magnetization precession at ferromagnetic resonance frequency.

Magnetization dynamics are driven by strain-induced changes in magnetic anisotropy.

The inverse magnetostriction effect explains the observed magnetization precession.

Abstract

Using femtosecond optical pulses, we have investigated the ultrafast magnetization dynamics induced in a dielectric film of bismuth-substituted yttrium iron garnet (Bi-YIG) buried below a thick Cu/Pt metallic bilayer. We show that exciting the sample from Pt surface launches an acoustic strain pulse propagating into the garnet film. We discovered that this strain pulse induces a coherent magnetization precession in the Bi-YIG at the frequency of the ferromagnetic resonance. The observed phenomena can be explain by strain-induced changes of magnetocristalline anisotropy via the inverse magnetostriction effect. These findings open new perspectives toward the control of the magnetization in magnetic garnets embedded in complex heterostructure devices.