THz Control of Exchange Mode in a Ferrimagnetic Cavity

2024/06/28 by Reinhoffer, Chris, Razdolski, Ilya, Stein, Philipp +4
#FOS: Physical sciences #Other Condensed Matter (cond-mat.other)

paper · doi:10.48550/arxiv.2406.19849

Abstract

The interaction of terahertz (THz) radiation with high-frequency spin resonances in complex magnetic materials is central for modern ultrafast magnonics. Here we demonstrate strong variations of the excitation efficiency of the sub-THz exchange magnon in a single crystal ferrimagnet (Gd,Bi)₃Fe₅O₁₂. An enhancement of the exchange magnon amplitude is observed when its frequency matches an eigenmode of the cavity created by the sample interfaces. Moreover, this enhancement is accompanied by a 5-fold decrease in effective damping of the exchange mode. The THz-exchange magnon interaction in the cavity is analyzed within the developed Landau-Lifshitz-Gilbert formalism for three coupled magnetization sublattices and cavity-enhanced THz field. This work presents a novel approach for the THz excitation of spin dynamics in ferrimagnets and outlines promising pathways for the controlled optimization of light-spin coupling in single crystals.

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