Ultrastrong Magnon-Photon Coupling Achieved by Magnetic Films in Contact with Superconducting Resonators
Alberto Ghirri, Claudio Bonizzoni, Maksut Maksutoğlu, Alberto Mercurio, Omar Di Stefano, Salvatore Savasta, M. Affronte
Abstract
Controlling magnon-photon coupling is one of the keys to enabling cavity magnonics in several emerging applications, where the realization of all-on-chip devices is crucial to integrating magnonic systems with microwave circuits. This study shows that ultrastrong coupling can be achieved with a ferrimagnetic film in direct contact with a superconducting resonator. Analysis shows that the diamagnetic coupling term is vanishingly small, suggesting a potential route to superradiant phase transitions. These results ought to be relevant for microwave technologies including memory devices, microwave-to-optical transducers, haloscopes for axion detection, and coherent microwave sources.