MAGNETIC-FIELD-EFFECT 3-TERMINAL DEVICE BASED ON YBA2CU3O7-DELTA GRAIN-BOUNDARY JUNCTIONS

Three-terminal YBa2Cu3O7-delta thin film devices based on a parallel a rray of grain boundary Josephson junctions were fabricated. The multil oop superconducting device is controlled by the magnetic field generat ed by a current I-ctrl, which modulates the critical current I-c throu gh the Josephson junction array. For these devices a current gain rang ing between 2 at 77 K and 5 at 30 K was obtained. The spatial homogene ity of the device properties was studied by low-temperature scanning e lectron microscopy and by the determination of the supercurrent correl ation function. Comparing the measured and the theoretically expected supercurrent correlation function shows that the device characteristic s agree well with those expected from the device geometry.