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arXiv · 2401.10671

Diversity of Ultrafast Spin Dynamics Near the Tricritical Point in a Ferrimagnetic Gd/FeCo Multilayer

T. G. H. Blank·B. D. Muis·T. Lichtenberg·B. Koopmans·A. V. Kimel
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Abstract

It is found that subtle changes in the external magnetic field and temperature result in dramatic changes in the ultrafast response of spins to a femtosecond laser excitation in a ferrimagnetic Gd/FeCo multilayer. A total of six distinct types of spin dynamics were observed and explained by considering the spin-flop transition to the noncollinear phase and the concept of a tricritical point in the $H$-$T$ phase diagram. A particularly interesting type of dynamics is the exchange-driven reversal. These exchange-driven dynamics provide new insights into the tricritical point, which is shown to separate two thermodynamically distinct noncollinear phases with the transition-metal magnetization pointing on adjacent sides of the anisotropy plane.

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T. G. H. Blank, B. D. Muis, T. Lichtenberg, B. Koopmans, A. V. Kimel. 2024-01-19. Diversity of Ultrafast Spin Dynamics Near the Tricritical Point in a Ferrimagnetic Gd/FeCo Multilayer. https://doi.org/10.1103/physrevb.110.l140404

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