Fabrication and characterization of intrinsic Josephson junctions in RE-123 whiskers

Abstract

The series of REBa 2Cu 3O 7−δ RE-123; RE = Y, Eu, Gd, Dy, Ho, Er, Tm, and Lu) single-crystal whiskers have been successfully grown using the Te- or Sb-doping method. Intrinsic Josephson junctions (IJJs) were fabricated from the whiskers using a focused ion beam (FIB). As-grown IJJs with T c > 70 K showed a Josephson current but no multi-branches in the current–voltage ( I–V) characteristics. Under-doped specimens were obtained by a post-annealing process. As-grown IJJs with lower T c and all the specimens of the post-annealed IJJs showed clear multi-branched structure. The post-annealing reduced the critical temperature ( T c) and the critical current density ( J c) of the IJJs, and increased the anisotropic parameter γ.