Niobium Nitride Resonators for Cavity Magnonics Devices

We investigate the performance of niobium nitride superconducting coplanar waveguide resonators towards hybrid quantum devices with magnon-photon coupling. We find internal quality factors ~20000 at 20 mK base temperature, in zero magnetic field. We find that by reducing film thickness below 100 nm internal quality factor greater than 1000 can be maintained up to parallel magnetic field of ~1 T and perpendicular magnetic field of ~100 mT. We demonstrate strong coupling of these resonators with an yttrium iron garnet sphere which suggests that these cavities will serve as a good platform for studying magnon-photon coupling in 2D ferromagnet based hybrid quantum systems.