Magnetic effects on THz superconducting tunnel junctions at different temperatures

Abstract

We have investigated the effect of a moderately strong magnetic field (generated by superconducting coil, up to 380Gauss, 6 quantum fluxes within a single junction; generated by one piece of permanent magnet; generated by two pieces of permanent magnets respectively) on Nb superconducting tunnel junctions at different temperatures. Both experimental and numerical results show that the superconducting tunnel junction DC Josephson current can be significantly reduced by a magnetic field. A relatively strong magnet field may suppress the gap voltage as well as the sharp nonlinearity at the gap. We also investigated the leakage current and DC Josephson current of the Nb SIS junction at different temperatures.