The effect of a pulse magnetic field on the microwave properties of a YBCO thin film strip-line resonator

The effect of a single pulse magnetic field on the resonant frequency and quality factor of an YBa2Cu3O7−δ thin film strip-line resonator was studied at different temperatures and input power levels. It was shown that: (i) the induced magnetic flux and screening dc current, resulting from the pulse action, noticeably change both the resonant frequency and the quality factor; and (ii) relaxation of the trapped flux and induced current, caused by the flux creep process (at rather high temperatures), lead to a time evolution of these resonator characteristics. This relaxation proceeds in two stages: quick relaxation during the first 1–2 s (at T = 78 K) and long term (logarithmic) relaxation. The rate of long term relaxation increases with temperature increase; on the other hand it does not depend on the input power level.