Abnormal anti-crossing effect in photon-magnon coupling

TL;DR

This paper demonstrates an unusual opposite anti-crossing effect in photon-magnon coupling systems, controllable by the orientation of split-ring resonators, with potential for advanced microwave device design.

Contribution

It introduces a method to invert the anti-crossing dispersion in photon-magnon systems by adjusting the ISRR split gap orientation, revealing new control over damping and coupling.

Findings

Opposite anti-crossing dispersion observed experimentally.

Control of dispersion shape via ISRR split gap orientation.

Analysis based on electromagnetic interaction models.

Abstract

We report the experimental demonstration of an abnormal, opposite anti-crossing effect in a photon-magnon-coupled system that consists of an Yttrium Iron Garnet film and an inverted pattern of split-ring resonator structure (noted as ISRR) in a planar geometry. It is found that the normal shape of anti-crossing dispersion typically observed in photon-magnon coupling is changed to its opposite anti-crossing shape just by changing the position/orientation of the ISRR's split gap with respect to the microstrip line axis along which ac microwave currents are applied. Characteristic features of the opposite anti-crossing dispersion and its linewidth evolution are analyzed with the help of analytical derivations based on electromagnetic interactions. The observed opposite anti-crossing dispersion is ascribed to the compensation of both intrinsic damping and coupling-induced damping in the magnon modes. This compensation is achievable by controlling the relative strength and phase of oscillating magnetic fields generated from the ISRR's split gap and the microstrip feeding line. The position/orientation of an ISRR's split gap provides a robust means of controlling the dispersion shape of anti-crossing and its damping in a photon-magnon coupling, thereby offering more opportunity for advanced designs of microwave devices.