Experiments are performed on an HTS transmission line fabricated with a series array of Josephson junctions. We have determined the phase shift mechanism and have measured the magnitude of the phase shift of wide junctions. A qualitative model of the phase shift mechanism has been developed which explains the effects of applied magnetic fields. (C) 1993 John Wiley & Sons, Inc.

YBa/sub 2/Cu/sub 3/O/sub 7/ (YBCO) step edge DC superconducting quantum interference devices (SQUIDs) have been developed which exhibit characteristics suitable for near-term incorporation into high-temperature superconductive (HTS) circuitry. Step-edge junction DC SQUIDs for series array interferometer logic (SAIL) digital applications exhibit resistively shunted junction (RSJ) properties, 65 K I/sub c/ values of approximately 150 mu A, 65 K I/sub c/R/sub n/ values up to approximately 300 mu V, and large I/sub c/ modulation (>50%) in accordance with a standard DC SQUID model. 65 K SQUID switching voltages of approximately 100 mu V have been demonstrated and are sufficient for near-term applications of SAIL digital circuitry operating on a cryocooler platform.< >

We describe a monolithic phase shifter which combines the low loss of high-temperature superconductivity (HTS) with the variable dielectric properties of a ferroelectric material SrTiO3. Phase shifts greater than 28 degrees per wavelength were observed around 30-degrees K. The compatibility of YBa2Cu3O7-x and other ferroelectric materials is discussed.

Step-edge Josephson junctions are engineered grain boundary junctions fabricated using standard lithographic and film deposition techniques. We report a systematic study of 180 YBa2Cu3O7 step-edge junctions and identify a fabrication technique which results in a 90% yield of working junctions with critical current spreads from 30% to 50% (1σ/Ic-ave)over the entire substrate. Technically useful critical current values at 65 K can be obtained by adjusting YBa2Cu3O7 film thickness. IcRn values, approximately independent of film thickness, are ∼1 mV at 4.2 K and ∼0.1 mV at 65 K. Most junctions exhibit ideal electrical behavior in accordance with the RSJ model.

A parallel-plate resonator technique previously used to measure microwave surface resistance R(s)(T) has been extended to also measure absolute penetration depth-lambda(T). Measurements of both quantities near 10 GHz from 4.2K to Tc are reported for ErBaCuO thin films produced by metal-organic chemical vapor deposition (MOCVD) and YBaCuO thin films produced by laser ablation and single-target off-axis sputtering. All the films were made at TRW. Each production method gives rise to films whose surface resistance is below 1 milliohm at temperatures below 40 K. The low temperature penetration depths range from 250 nm for the laser ablation and sputtered films to 800 nm for the MOCVD films. The penetration depths in all cases increase with temperature according to the Gorter-Casimir temperature dependence.