YBCO step-edge junction d.c. SQUIDs have been realized by using the Inverted Cylindrical Magnetron Sputtering (ICMS) technique. This last represents a novel technology for high-T-c Josephson junctions (HTSC). Steps are obtained by standard ion milling procedure on LaAlO3 (100) substrates using Nb-masks patterned by reactive ion etching. Measurements of current vs. voltage, maximum d.c. Josephson current vs. magnetic field and SQUID voltage response measurements have been performed, also as a function of the temperature. Operating temperature as high as 77K has been achieved. At 4.2 K the SQUIDs show a maximum voltage to flux transfer function (partial derivative V/partial derivative phi)(max) = 870 mu V/Phi(0) and a good periodicity of the V-phi modulation up to 20 Phi(0) without any sign of hysteresis. The ratio between the step height (h) and the film thickness (d) seems to play a fundamental role in determining Josephson properties of the bridges, these conditions being more severe with respect to most of the data available in literature.
YBCO STEP-EDGE SQUIDS BY MAGNETRON SPUTTERING TECHNIQUE
GRANOZIO;TAFURI F;VALENTINO M;PAGANO S;RUGGIERO B;
1994
Abstract
YBCO step-edge junction d.c. SQUIDs have been realized by using the Inverted Cylindrical Magnetron Sputtering (ICMS) technique. This last represents a novel technology for high-T-c Josephson junctions (HTSC). Steps are obtained by standard ion milling procedure on LaAlO3 (100) substrates using Nb-masks patterned by reactive ion etching. Measurements of current vs. voltage, maximum d.c. Josephson current vs. magnetic field and SQUID voltage response measurements have been performed, also as a function of the temperature. Operating temperature as high as 77K has been achieved. At 4.2 K the SQUIDs show a maximum voltage to flux transfer function (partial derivative V/partial derivative phi)(max) = 870 mu V/Phi(0) and a good periodicity of the V-phi modulation up to 20 Phi(0) without any sign of hysteresis. The ratio between the step height (h) and the film thickness (d) seems to play a fundamental role in determining Josephson properties of the bridges, these conditions being more severe with respect to most of the data available in literature.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
