Demagnetization dynamics after noncollinear dual optical excitation

TL;DR

This study investigates how interfering ultrashort optical pulses influence ultrafast magnetization dynamics in multilayer and alloy samples, revealing novel effects of optical interference on demagnetization and recovery processes.

Contribution

It introduces the concept that interfering light can induce long-lasting changes in magnetization dynamics, a previously unrecognized phenomenon in ultrafast magnetism.

Findings

Interfering pulses significantly alter demagnetization and recovery dynamics.

Cross-polarized pulses produce dynamics similar to single pulses.

Current models cannot fully explain the observed effects.

Abstract

We explore the impact of optical excitation using two interfering ultrashort optical pulses on ultrafast magnetization dynamics. Our investigation focuses on Pt/Co/Pt multilayers and TbCo alloy samples, employing a dual pump approach. We observe significant variations in the dynamics of magnetization suppression and subsequent recovery when triggered with two optical pulses of the same polarization-essentially meeting conditions for interference. Conversely, dynamics triggered with cross-polarized pump beams exhibit expected similarity to that triggered with a single pulse. Delving into the underlying physical processes contributing to laser-induced demagnetization and recovery dynamics, we find that our current understanding cannot elucidate the observed trends. Consequently, we propose that optical excitation with interfering light possesses not previously acknowledged capacity to induce long-lasting alterations in the dynamics of angular momentum.