Tunneling investigation of high T c Bi-system films on SrTiO 3 (110)

Abstract

The tunneling measurements were performed for the Pb-SiO-High Tc Bi-system film sandwich type junctions at temperatures ranging from 4.2 K to 79.8 K and under magnetic fields between 0 kOe and 12.4 kOe. Two kinds of spectrum were obtained. The one at 4.2 K gives 2Δ=21 meV and another one at 4.2 K 2Δ=47 meV. Using Tc=65 K for the film, we get the coupling strength factors, 2Δ0/kTc=3.8 for 2Δ=21 meV and 2Δ0/kTc=8.4 for 2Δ=47 meV. The temperature dependence of superconducting-gap is found to be very weaker than the BCS prediction. Further, it was found that a subgap inside superconducting-gap disappears under magnetic field of 12.4 kOe.