Improved time-resolved magneto-optical Kerr effect technique and dynamic magnetization reversal mechanism of perpendicularly magnetized $L1_{\mathrm{0}}$ FePt films

TL;DR

This paper introduces an improved time-resolved magneto-optical Kerr effect technique using an alternating magnetic field synchronized with femtosecond laser pulses to accurately measure dynamic coercivity and investigates the magnetization reversal mechanism in $L1_{0}$ FePt films.

Contribution

The study presents a novel measurement method that eliminates accumulation effects and reveals the nucleation and domain wall motion as key processes in magnetization reversal.

Findings

Enhanced measurement accuracy of dynamic coercivity.

Identification of nucleation and domain wall motion in magnetization reversal.

Effective removal of irreversible deviation accumulation.

Abstract

The dynamic coercivity cannot be measured rigorously by the conventional time-resolved magneto-optical Kerr effect technique because the irreversible deviation of the transient magnetization is accumulated. In order to remove the accumulation effect, the alternating magnetic field is employed and synchronized with the femtosecond laser pulse. Since the sample is reset before each single laser pulse, the accumulation effect of the irreversible deviation of the transient magnetization is removed. For perpendicularly magnetized $L1_{\mathrm{0}}$ FePt films, the dynamic magnetization reversal process is accomplished by the nucleation of reversed domains and the pinned domain wall motion.