Properties of c-axis Josephson tunneling between Bi2Sr2CaCu2O8 and Nb

We have fabricated well-defined c-axis Bi2Sr2CaCu2O8 (BSCCO)/Au/Nb junction s on cleaved surfaces of BSCCO single crystal and observed typical current- voltage characteristics of Josephspn tunnel junctions, A magnetic field dep endence of the supercurrent shows that a zero bias current is not a leakage from some pin-holes, but a Josephson current, These results strongly indic ate a presence of an s-wave component in BSCCO, The results of the temperat ure dependence of the Josephson current indicate that the superconducting g ap for the s-wave component in BSCCO is about 10(-3) of the d-wave componen t, and that the T-c, of the a-wave is about 10 K. (C) 1999 Elsevier Science B.V. All rights reserved.