Accelerating the laser-induced demagnetization of a ferromagnetic film by antiferromagnetic order in an adjacent layer

TL;DR

This study demonstrates that antiferromagnetic order in an adjacent layer accelerates laser-induced demagnetization in ferromagnetic films, revealing the role of magnetic order in ultrafast spin dynamics.

Contribution

It provides new insights into how antiferromagnetic order influences ultrafast demagnetization, highlighting the role of superdiffusive spin currents between layers.

Findings

Antiferromagnetic order speeds up ferromagnetic demagnetization.

Superdiffusive spin currents mediate the interaction.

Temperature tuning reveals the effect of magnetic order.

Abstract

We study the ultrafast demagnetization of Ni/NiMn and Co/NiMn ferromagnetic/antiferromagnetic bilayer systems after excitation by a laser pulse. We probe the ferromagnetic order of Ni and Co using magnetic circular dichroism in time-resolved pump--probe resonant X-ray reflectivity. Tuning the sample temperature across the antiferromagnetic ordering temperature of the NiMn layer allows to investigate effects induced by the magnetic order of the latter. The presence of antiferromagnetic order in NiMn speeds up the demagnetization of the ferromagnetic layer, which is attributed to bidirectional laser-induced superdiffusive spin currents between the ferromagnetic and the antiferromagnetic layer.