Dynamics of femtosecond magnetization reversal induced by circularly polarized light in the presence of fluctuations and dissipation

TL;DR

This paper investigates the mechanisms behind femtosecond magnetization reversal induced by circularly polarized light, challenging previous explanations and proposing a new model involving symmetry reduction and enhanced spin-orbit coupling.

Contribution

It introduces a novel mechanism for femtosecond magnetization reversal that does not rely on thermal effects, emphasizing the role of symmetry and spin-orbit interactions in RE-TM systems.

Findings

The inverse Faraday effect and thermal effects are unlikely to cause femtosecond reversal based on experimental parameters.

A new model involving symmetry reduction and enhanced spin-orbit coupling explains the reversal.

The proposed mechanism does not require heating near the Curie temperature.

Abstract

Magnetization reversal by a femtosecond circularly polarized laser pulse has been recently demonstrated in rare-earth doped transition metals (RE-TM). The switching mechanism has been attributed to an inverse Faraday effect and thermal effects. Based on the parameters provided in the experimental work, we show that this claim is unlikely to give rise to femtosecond reversal. Using a hybrid itinerant-localized picture of the RE-TM system, we propose a new mechanism that requires the presence of the rare earth element to reduce the symmetry of the system as well as a strong enhancement of spin-orbit coupling between the d electrons and the f moments in the presence of the laser. Our model does not require the heating close to the Curie temperature of the sample.