Excitation and coherent control of magnetization dynamics in magnetic tunnel junctions using acoustic pulses

TL;DR

This study demonstrates how femtosecond laser-induced surface acoustic waves can coherently control magnetization precession in magnetic tunnel junctions, revealing localized edge modes and potential for ultrafast spin manipulation.

Contribution

It introduces a novel experimental approach using acoustic pulses to control magnetization dynamics in magnetic tunnel junctions, highlighting coherent control and localized mode identification.

Findings

Acoustic pulses induce magnetization precession via magnetoelastic coupling.

Precession frequency depends on magnetic field and laser position.

Coherent control achieved with two acoustic pulses.

Abstract

We experimentally study magnetization dynamics in magnetic tunnel junctions driven by femtosecond-laser-induced surface acoustic waves. The acoustic pulses induce a magnetization precession in the free layer of the magnetic tunnel junction through magnetoelastic coupling. The frequency and amplitude of the precession shows a pronounced dependence on the applied magnetic field and the laser excitation position. Comparing the acoustic-wave-induced precession frequencies with precession induced by charge currents and with micromagnetic simulations we identify spatially non-uniform magnetization modes localized close the edge regions as being responsible for the optically induced magnetization dynamics. The experimental scheme even allows us to coherently control the magnetization precession using two acoustic pulses. This might prove important for future applications requiring ultrafast spin manipulation. Additionally, our results directly pinpoint the importance of acoustic pulses since they could be relevant when investigating optically-induced temperature effects in magnetic structures.