YBa_2Cu_3O_(7-x) Josephson junctions on NdGaO_3 bicrystal substrates

摘要

The results of electrical characterization of YBa_2Cu_3O_(7-x) grain-boundary junctions made on NdGaO_3 bicrystal substrates without twins are reported. The spatially-resolved electrical measurements of weak links in the junctions have been carried out by Laser Scanning Microscopy with submicrometer resolution. RSJ-like behavior has been observed for grain-boundary junctions with I_c * R_n product up to 3 mV at liquid helium temperatures and up to 0.3 mV at liquid nitrogen. Pure sincp-dependence of current-phase relationship in the Josephson junctions made on NdGaO_3 bicrystal substrates has been confirmed by measurements of the dc response of these junctions to weak electromagnetic radiation in the frequency range from 400 GHz to 1.8 THz. A Lorentzian shape of spectra of Josephson oscillations in these junctions has been demonstrated by Hilbert-Transform Spectroscopy.