In-plane tunneling spectroscopy in Bi2Sr2CaCu2O8+δ–SiO–Ag planar junctions

We report the experimental results of quasiparticle tunneling using Bi2Sr2CaCu2O8+δ–SiO–Ag planar junctions. We have measured the {001}-, {100}- and {110}-oriented junctions. For the in-plane ab oriented junctions, a reproducible zero bias conductance peak has been observed. We have analyzed the data by using the extended Andreev bound states model for d-wave superconductors and have considered the roughness effect by averaging over in-plane directions. The experimental results are consistent with the theoretical calculations.