Lattice structure dependence of laser-induced ultrafast magnetization switching in ferrimagnets

TL;DR

This study investigates how the lattice structure influences laser-induced ultrafast magnetization switching in ferrimagnets, revealing that fewer exchange-coupled neighbors lower the energy threshold for switching.

Contribution

It combines phenomenological theory with atomistic simulations to show lattice structure impacts magnetization dynamics and switching thresholds in ferrimagnetic alloys.

Findings

Switching depends on the number of exchange-coupled neighbors.

Critical laser energy decreases with fewer neighbors.

Lattice structure significantly influences ultrafast magnetization dynamics.

Abstract

The experimental discovery of single-pulse ultrafast magnetization switching in ferrimagnetic alloys, such as GdFeCo and MnRuGa, opened the door to a promising route toward faster and more energy efficient data storage. A recent semi-phenomenological theory has proposed that a fast, laser-induced demagnetization below a threshold value puts the system into a dynamical regime where angular momentum transfer between sublattices dominates. Notably, this threshold scales inversely proportional to the number of exchange-coupled nearest neighbours considered in the model, which in the simplest case is directly linked to the underlying lattice structure. In this work, we study the role of the lattice structure on the laser-induced ultrafast magnetization switching in ferrimagnets by complementing the phenomenological theory with atomistic spin dynamics computer simulations. We consider a spin model of the ferrimagnetic GdFeCo alloy with increasing number of exchange-coupled neighbours. Within this model, we demonstrate that the laser-induced magnetization dynamics and switching depends on the lattice structure. Further, we determine that the critical laser energy for switching reduces for decreasing number of exchange-coupled neighbours.