RF coupling to single crystal BSCCO under c-axis bias

We have explored rf coupling to BSCCO single crystals with c-axis bias currents over a wide range of frequencies. A structure was developed that afforded the necessary impedance transformations at several frequencies from dc to 35 GHz. At low frequencies, connections were made to a coaxial cable. At X-band, the sample was placed in front of a short section of waveguide, forming a resonator. Above 12 GHz, the sample mount formed a coplanar resonator. At 35 GHz it was used as the end plate of a cylindrical cavity with degenerate mode spoilers and a loaded Q-factor of 3800 at 38.3 GHz. Fabricated BSCCO samples showed evidence of hysteretic Josephson junction stack behavior at 77 K. Application of low frequency rf signals caused steps to appear in the sample I-V. At frequencies above 6.4 GHz only a reduction of critical current was observed.<
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