Laser-induced demagnetization in a MAX phase (Cr0.5Mn0.5)2GaC

TL;DR

This study investigates ultrafast laser-induced demagnetization in a magnetic MAX phase thin film, revealing a two-step demagnetization process and providing insights for optical control of magnetism in 2D spintronics.

Contribution

First detailed investigation of laser-induced ultrafast demagnetization dynamics in a magnetic MAX phase using time-resolved Kerr spectroscopy.

Findings

Revealed a two-step type-II demagnetization process.

Identified a characteristic demagnetization time of approximately 100 ps.

Extracted electron-lattice, spin-lattice, and electron-spin coupling constants.

Abstract

Magnetic MAX phases are nanolaminated metals that combine ceramic-like thermal and mechanical stability with peculiar magnetic ordering, making them attractive for thin-film optoelectronics and spintronics. However, their magnetization dynamics remain largely unexplored. Here, we investigate laser-induced ultrafast demagnetization in a 40-nm-thick epitaxial film of the magnetic MAX phase (Cr0.5Mn0.5)2GaC, which magnetically orders below ~250 K, using time-resolved magneto-optical Kerr effect spectroscopy. We reveal, that the demagnetization transients exhibit a two-step type-II demagnetization - a signature of two-dimensional magnetic systems. The fast demagnetization stage is small at low temperatures and fluences but becomes prominent with increasing excitation. The second stage dominates the process and has a characteristic time of approximately 100 ps. Applying the three-temperature model, we extract the electron-lattice, spin-lattice, and electron-spin coupling constants. The reconstructed spin heat capacity exhibits a weak temperature dependence, accounting for the absence of significant slowing down of demagnetization at elevated temperatures and fluences. Our results provide a starting point for experimental optical control of magnetism in MAX phases, bringing this broad class of materials into modern 2D spintronics.