THz Control of Exchange Mode in a Ferrimagnetic Cavity

Chris Reinhoffer; Ilya Razdolski; Philipp Stein; Semyon Germanskiy; Andrzej Stupakiewicz; Paul H. M. van Loosdrecht; Evgeny A. Mashkovich

arXiv · 2406.19849

THz Control of Exchange Mode in a Ferrimagnetic Cavity

Chris Reinhoffer·Ilya Razdolski·Philipp Stein·Semyon Germanskiy·Andrzej Stupakiewicz·Paul H. M. van Loosdrecht·Evgeny A. Mashkovich

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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)$_3$Fe$_5$O$_{12}$. 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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Chris Reinhoffer, Ilya Razdolski, Philipp Stein, Semyon Germanskiy, Andrzej Stupakiewicz, Paul H. M. van Loosdrecht, Evgeny A. Mashkovich. 2024-06-28. THz Control of Exchange Mode in a Ferrimagnetic Cavity. https://arxiv.org/abs/2406.19849

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