Search

Submicron YBa[sub 2]Cu[sub 3]O[sub x]/PrBa[sub 2]Cu[sub 2.6]Ga[sub 0.4]O[sub x]/YBa[sub 2]Cu[sub 3]O[sub x] ramp-type Josephson junctions were fabricated and tested. The submicron bridges in the top electrode were patterned by e-beam lithography and Ar ion milling through an amorphous carbon (a-C) mask. Junctions with width ranging from 0.2 to 8 μm and oriented along different crystal directions of YBa[sub 2]Cu[sub 3]O[sub x] have been produced. Current–voltage characteristics show a behavior consistent with the resistively shunted junction model with small excess current. Junction critical current densities of about 10 kA/cm[sup 2] and characteristic voltages up to 6 mV were measured at 4.2 K for the submicron junctions. Junctions along different crystal orientations showed different characteristics suggesting an influence from the d-wave order parameter. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We discuss the properties of sub-micron YBa2Cu3O7−δ step-edge Josephson junctions and their application in micro-SQUIDs. We suggest a design of a micro-SQUID sensor for the scanning SQUID microscopy. Two methods of coupling the modulation and feedback signals to the sensor are described. Influence of a superconducting sample on the sensor parameters is analyzed for the two configurations. [Copyright &y& Elsevier]