Properties of Superconductive Strip-line Resonators Fabricated Using EuBaCuO Films on MgO (100)

Abstract

This paper reports on the properties of superconductive strip-line resonators fabricated using EuBaCuO superconducting films on MgO (100) substrates. A high loaded-Q of 22000 and an unloaded-Q of 24000 are realized at 35.5 K and 5.55 GHz. The surface resistance is calculated as 160 µΩ without any correction and 50 µΩ with t/λ correction. In addition, a resonant frequency shift of 40 MHz occurs in the measurement range. This shift can be mainly explained by the reduction in penetration depth due to the decrease in temperature. From this shift, penetration depth at 0 K is estimated to be 0.75 µm. Furthermore, there is no change in the unloaded-Q in the power region below -10 dBm, but then the unloaded-Q gradually decreases as the input power is increased although the penetration depth hardly varies. This limitation does not indicate that the whole superconductive phase is weakened. The influence of air spacing on resonant frequency is also discussed for MgO and LaAlO₃ substrates.