Probing magnon-magnon coupling in exchange coupled Y$_3$Fe$_5$O$_{12}$/Permalloy bilayers with magneto-optical effects

TL;DR

This paper demonstrates magnetically-induced transparency in YIG/Py bilayers through magneto-optical effects, revealing magnon-magnon coupling and providing a new approach to study phase-resolved spin dynamics in hybrid magnonic systems.

Contribution

It introduces a novel experimental method to observe magnon-magnon coupling via magneto-optical effects and develops a phenomenological model matching the experimental data.

Findings

Observation of magnetically-induced transparency in YIG/Py bilayers

Development of a phenomenological model for magnon-magnon coupling

Potential for phase-resolved spin dynamics studies

Abstract

We demonstrate the magnetically-induced transparency (MIT) effect in Y$_3$Fe$_5$O$_{12}$(YIG)/Permalloy(Py) coupled bilayers. The measurement is achieved via a heterodyne detection of the coupled magnetization dynamics using a single wavelength that probes the magneto-optical Kerr and Faraday effects of Py and YIG, respectively. Clear features of the MIT effect are evident from the deeply modulated ferromagnetic resonance of Py due to the perpendicular-standing-spin-wave of YIG. We develop a phenomenological model that nicely reproduces the experimental results including the induced amplitude and phase evolution caused by the magnon-magnon coupling. Our work offers a new route towards studying phase-resolved spin dynamics and hybrid magnonic systems.