Alexandra Kalashnikova

arXiv2026

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

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, laser-induced magnetization dynamics in MAX phases remains 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 ~220 K, using time-resolved magneto-optical Kerr effect spectroscopy. We reveal, that the demagnetization transients exhibit a two-step type-II demagnetization, common for two-dimensional magnetic systems. 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 only a subtle slowing down of demagnetization at elevated temperatures and fluences.

cond-mat.mtrl-sci↗

arXiv2016

Exchange scattering as the driving force for ultrafast all-optical and bias-controlled reversal in ferrimagnetic metallic structures

Experimentally observed ultrafast all-optical magnetization reversal in ferrimagnetic metals and heterostructures based on antiferromagnetically coupled ferromagnetic $d-$ and $f-$metallic layers relies on intricate energy and angular momentum flow between electrons, phonons and spins. Here we treat the problem of angular momentum transfer in the course of ultrafast laser-induced dynamics in a ferrimagnetic metallic system using microscopical approach based on the system of rate equations. We show that the magnetization reversal is supported by a coupling of $d-$ and $f-$ subsystems to delocalized $s-$ or $p-$ electrons. The latter can transfer spin between the two subsystems in an incoherent way owing to the $(s;p)-(d;f)$ exchange scattering. Since the effect of the external excitation in this process is reduced to the transient heating of the mobile electron subsystem, we also discuss possibility to trigger the magnetization reversal by applying a voltage bias pulse to antiferromagnetically coupled metallic ferromagnetic layers embedded in point contact or tunneling structures. We argue that such devices allow controlling reversal with high accuracy. We also suggest to use the anomalous Hall effect to register the reversal, thus playing a role of reading probes.

cond-mat.str-el↗