JOSEPHSON VORTEX-FLOW TRANSISTORS BASED ON PARALLEL ARRAYS OF YBA2CU3O7-DELTA BICRYSTAL GRAIN-BOUNDARY JUNCTIONS

Three-terminal electronic devices based on flux-flow phenomena have attracted considerable interest due to their potential application in the interface between superconducting and semiconducting electronics. We have fabricated Josephson vortex flow transistors based on parallel arrays of YBa2Cu3O7-delta (YBCO) bicrystal Grain Boundary Junctions (GBJs). The array critical current I-c has been measured as a function of an external magnetic field B or the magnetic field of the current I-ctrl that is fed through the control line coupled inductively to the array. By varying the device geometry we have studied the influence of the coupling of the magnetic control and the array parameters such as the number N of discrete Josephson elements and the screening parameter beta(L) on the I-c(B) dependences of the arrays. Going from beta(L) much less than 1 to beta(L) much greater than 1 the measured I-c(B) curves changed from a dependence similar to the diffraction pattern of a grid to a dependence dominated by the parameters of a single array cell. The impact on the available current gain is discussed.