Strong Coupling between Magnons and Microwave Photons in On-Chip Ferromagnet-Superconductor Thin-Film Devices

We demonstrate strong magnon-photon coupling of a thin-film Permalloy device fabricated on a coplanar superconducting resonator. A coupling strength of 0.152 GHz and a cooperativity of 68 are found for a 30-nm-thick Permalloy stripe. The coupling strength is tunable by rotating the biasing magnetic field or changing the volume of Permalloy. We also observe an enhancement of magnon-photon coupling in the nonlinear regime of the superconducting resonator, which is attributed to the nucleation of dynamic flux vortices. Our results demonstrate a critical step towards future integrated hybrid systems for quantum magnonics and on-chip coherent information transfer.Received 25 February 2019DOI:https://doi.org/10.1103/PhysRevLett.123.107701© 2019 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasMagnonsQuantum information with hybrid systemsSuperconducting RFPhysical SystemsLow-temperature superconductorsSuperconducting devicesTechniquesCavity resonatorsCondensed Matter, Materials & Applied Physics