Effect of Pulse Magnetic Field on Microwave Properties of YBCO Thin Film Strip-Line Resonator

This work investigates the effect of single pulse magnetic field on microwave characteristics of YBCO thin film strip-line resonator such as the quality factor Q and resonant frequency F, and their evolution during the flux creep process at different temperatures and input power levels. It was shown that: (i) induced magnetic flux and screening dc current, resulting from the pulse action, noticeably change both resonant frequency and quality factor; (ii) relaxation of the trapped flux and pulse-induced current, caused by flux creep process (at rather high temperatures) lead to time evolution of these resonator characteristics. This relaxation proceeds in two stages: quick relaxation during the first 1-2 seconds (at T=78 K) and long term (logarithmic) relaxation. The rate of long term relaxation increases with temperature increase; on the other hand it doesn´t depend on the input power level.