Nonreciprocity and Unidirectional Invisibility in Cavity Magnonics

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.Received 23 June 2019DOI:https://doi.org/10.1103/PhysRevLett.123.127202© 2019 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasDissipative dynamicsExtraordinary optical transmissionMagnetization dynamicsMagnonsPolaritonsPhysical SystemsMagnetic insulatorsTechniquesCavity resonatorsCoherent controlCoupled mode theoryFerromagnetic resonanceMicrowave techniquesS-matrix method in transportCondensed Matter, Materials & Applied Physics