High-temperature superconducting Josephson fluxon-antifluxon transistors

We have realized the Josephson fluxon-antifluxon transistor (JFAT) in high temperature superconductivity using an asymmetric control line on top of either bicrystal junctions or Go-doped YBa2Cu3Ox superconductor-normal-superconductor (SNS) junctions. We have measured current gains as high as 6 for 30 mu m-wide bicrystal JFATs (30 K) and as high as 3 for Go-doped SNS JFATs (50 K). An improvement in gain over the Josephson vortex flow transistor, due to improved coupling efficiency, is demonstrated. There is also a reduction of control line inductance that should lead to an improvement in gate speed. (C) 1996 American Institute of Physics.