DC-SQUID MAGNETOMETERS AND GRADIOMETERS ON THE BASIS OF QUASIPLANAR RAMP-TYPE JOSEPHSON-JUNCTIONS

Nonaqueous Br-ethanol chemical etching was successfully used for (line preparation of the Josephson junctions, vias and crossovers in magnet ometers including flux transformers. PrBa2Cu3O7-x thin films were used for the barrier layer in the Josephson junctions of the SQUIDs and as an insulation in the junctions and in the flux transformers. Dc-SQUID magnetometers with small inductances and even without flux antennas w ere used for NDE applications which mainly require a high dynamic rang e. Highly sensitive devices were prepared with flip-chip flux antennas . An ac-bias SQUID electronics significantly improves the! sensitivity of the magnetometers at low frequencies.