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An investigation is presented into the return current distribution for a high-quality Nb/AlOx/Nb Josephson junction, at liquid-helium temperature.

The electrons of a 3 cubic micron copper strip was cooled down via a superconductor-insulator-normal-insulator-superconductor (SINIS) structure. An electron temperature decrease of -10 mK was obtained at a temperature of the bath slightly above 500 mK. Findings do not agree with previous studies as the result was attained by operating with a simple 3He refrigerator. The copper strip temperature change was detected by measuring the voltage change across a current-biased SINIS junction.

A low 1/f flux noise YBa2Cu3O7-x bicrystal dc-superconducting quantum interference device was fabricated using the cylindrical magnetron sputtering method. The experimental values of the magnetic flux-to-voltage transfer parameter obtained were lower than expected. Using wide band reversal electronics, the 1/f noise levels were reduced. Single large magnetometers working at 77 K were also assembled, where a relatively high value of the flux to field transfer factors was achieved.

A thin-film second-order gradiometer with integrated dc-SQUID has the potential to be used in studies where magnetic sensor arrays are needed. The device is based on a 12.8 times 12.8 mm silicon chip, on which the same four 0.5 mm square holes produce the SQUID inductance and the sensitive area of the gradiometer. The gradiometer in the FLL mode determines the distribution of the magnetic isoflux line which is produced by a dipolar source.

The magnetic-field-induced singularities in the Fiske steps of the current-voltage characteristics of a Josephson tunnel junction operating in cavity-mode excitations at millimeter-wave frequencies were investigated. The mode of operation of the junction was characterized in terms of the applied current and magnetic field bias. Results indicate that is is possible to couple a Josephson junction operating under such condition to external devices.

Research describing the characteristics of superconducting single electron transistors is presented. In particular the charge noise and transport properties are investigated.

Electrical characteristics of superconducting meanders with very different filling factors and that have applications as single-photon detectors are studied in detail. It is found that heating effects are important in explaining the full current-voltage characteristics of devices and the analysis of the current switching distributions of the stripes of the meander brings to the fore the high-critical current uniformity achieved by the meander process.

A hysteretic dc-superconducting quantum interference device (SQUID) configured as a flux comparator can be used as a proportional magnetometer. This technique is used to accurately trace the tunable rf-SQUID characteristics.

Postannealed structure and electron transport properties of magnetic tunnel junctions were compared to the conventional plasma oxidized junctions. Magnitude of spin polarized tunneling current being sensitive, alters the electrical properties of magnetic tunnel junctions.