Active high power switches based on Y-Ba₂-Cu₃-O_7-δ thin films

Active switching of nonshunted Y-Ba-Cu-O (YBCO) films has been observed. Films of 300 nm thickness were deposited on substrates by thermal co-evaporation, and afterwards bridges of 10 × 42mm² were structured by standard photolithography. No topcoat of gold was used to retain higher switching powers. The active switching of the DC-biased YBCO bridges was triggered by radio frequency pulses generated by a resonant circuit. The pancake coil of this resonant circuit was placed 1 mm above the 10 mm wide YBCO bridge. Once immersed in liquid nitrogen, the strips were biased by currents up to 40 A and triggered with RF-pulses of >1 ms duration and 3-30 W (10 MHz). Active switching was achieved. In comparison to a thermally triggered switching mechanism we previously investigated, the power required for RF induced switching is very low.