CONDUCTANCE PEAK AT ZERO-BIAS IN AG-SIO-BI2SR2CACU2O8-X PLANAR TUNNEL-JUNCTIONS

Two kinds of junctions were fabricated on a single crystal and a polyc rystal of Bi2Sr2CaCu2Odelta-x. The tunneling conductance characteristi cs, G(V) were measured for the former junction at temperatures from 4. 2 K to 100 K; and for the latter one at temperatures from 8.7 K to 90 K. It was found that the conductance peak (CP) at zero-bias is observe d for tunneling direction perpendicular to a c-axis, but is not observ ed for tunneling direction parallel to a c-axis. Kashiwaya et al, theo retically predicted that the junction fabricated on a d-wave supercond uctor can give various G(V) characteristics scattering from a s-wave l ike spectrum to a d-wave like one, and has CP under certain boundary c ondition. In the present investigation, the measured G(V) characterist ics in the high T-c Bi-system superconductor were found to qualitative ly agree with the theoretical prediction by Kashiwaya et al.