Superconducting microstrip resonator with yttrium iron garnet single crystals

A magnetically tunable microstrip superconducting resonator using an yttrium-iron-garnet (YIG) single crystal was demonstrated experimentally. Tunability of 200 MHz at a center frequency of 5.3 GHz was observed, and a quality factor of 965 with minimum insertion loss of 19.5 dB was measured for a half-wavelength microstrip line consisting of a YIG-YBCO-MgO composite structure. The dispersion relation of the resonator was analyzed using the spectral-domain method and discussed with experimental results on the mixed states of TEM and magnetostatic-wave modes. Power dependence of the characteristics is also discussed.