Nonreciprocity and Unidirectional Invisibility in Cavity Magnonics

TL;DR

This paper demonstrates how the interplay of coherent and dissipative magnon-photon couplings in cavity magnonics enables nonreciprocal microwave transmission and unidirectional invisibility, with potential applications in controllable microwave devices.

Contribution

It introduces a new mechanism combining coherent and dissipative couplings to achieve nonreciprocity and unidirectional invisibility in cavity magnonic systems.

Findings

Achieved large isolation ratio for microwave signals.

Discovered unidirectional invisibility at zero damping.

Developed a simple interference model explaining the phenomena.

Abstract

We reveal the cooperative effect of coherent and dissipative magnon-photon couplings in an open cavity magnonic system, which leads to nonreciprocity with a considerably large isolation ratio and flexible controllability. Furthermore, we discover unidirectional invisibility for microwave propagation, which appears at the zero-damping condition for hybrid magnon-photon modes. A simple model is developed to capture the generic physics of the interference between coherent and dissipative couplings, which accurately reproduces the observations over a broad range of parameters. This general scheme could inspire methods to achieve nonreciprocity in other systems.