Study of strong photon-magnon coupling in a YIG-film split-ring resonant system

TL;DR

This paper demonstrates strong photon-magnon coupling in a YIG-film split-ring resonator, revealing anti-crossing behavior and proposing an equivalent circuit model to explain the phenomena, with implications for quantum photonics and tunable metamaterials.

Contribution

It presents the first experimental observation of strong coupling in a planar YIG-based SRR system and introduces a theoretical circuit model that aligns with experimental results.

Findings

Coupling strength reaches 9% at 3 GHz.

Strong anti-crossing observed between photon and magnon modes.

Equivalent circuit model accurately explains mode anti-crossing.

Abstract

By using the stripline Microwave Vector Network Analyzer Ferromagnetic Resonance and Pulsed Inductive Microwave Magnetometry spectroscopy techniques, we study a strong coupling regime of magnons to microwave photons in the planar geometry of a lithographically formed split-ring resonator (SRR) loaded by a single-crystal epitaxial yttrium-iron garnet (YIG) film. Strong anti-crossing of the photon modes of SRR and of the magnon modes of the YIG film is observed in the applied-magnetic-field resolved measurements. The coupling strength extracted from the experimental data reaches 9 percent at 3 GHz. Theoretically, we propose an equivalent circuit model of an SRR loaded by a magnetic film. This model follows from the results of our numerical simulations of the microwave field structure of the SRR and of the magnetization dynamics in the YIG film driven by the microwave currents in the SRR. The equivalent circuit model is in good agreement with the experiment. It provides a simple physical explanation of the process of mode anti-crossing. Our findings are important for future applications in microwave quantum photonic devices as well as in magnetically tunable metamaterials exploiting the strong coupling of magnons to microwave photons.