All-optical spin switching probability in [Tb/Co] multilayers

TL;DR

This study uses atomistic simulations to explore all-optical spin switching in [Tb/Co] multilayers, revealing conditions for thermally-induced magnetization reversal and the influence of multilayer composition and interface mixing.

Contribution

It provides the first prediction of thermally-induced all-optical switching in [Tb/Co] multilayers and analyzes how multilayer structure affects switching stochasticity.

Findings

Thermally-induced switching observed in [Tb1/Co2] and [Tb1/Co3] multilayers.

Switching mechanism involves residual Tb magnetization and Co demagnetization.

Interface intermixing reduces stochasticity of the switching process.

Abstract

Since the first experimental observation of all-optical switching phenomena, intensive research has been focused on finding suitable magnetic systems that can be integrated as storage elements within spintronic devices and whose magnetization can be controlled through ultra-short single laser pulses. We report here atomistic spin simulations of all-optical switching in multilayered structures alternating n monolayers of Tb and m monolayers of Co. By using a two temperature model, we numerically calculate the thermal variation of the magnetization of each sublattice as well as the magnetization dynamics of [Tbn/Com] multilayers upon incidence of a single laser pulse. In particular, the condition to observe thermally-induced magnetization switching is investigated upon varying systematically both the composition of the sample (n,m) and the laser fluence. The samples with one monolayer of Tb as [Tb1/Co2] and [Tb1/Co3] are showing thermally induced magnetization switching above a fluence threshold. The reversal mechanism is mediated by the residual magnetization of the Tb lattice while the Co is fully demagnetized in agreement with the models developed for ferrimagnetic alloys. The switching is however not fully deterministic but the error rate can be tuned by the damping parameter. Increasing the number of monolayers the switching becomes completely stochastic. The intermixing at the Tb/Co interfaces appears to be a promising way to reduce the stochasticity. These results predict for the first time the possibility of TIMS in [Tb/Co] multilayers and suggest the occurrence of sub-picosecond magnetization reversal using single laser pulses.