A particle hole asymmetric conductance spectra tunneling into an atomically flat (100) YBCO surface was investigated through a nonmagnetic insulator. The tunnel junctions were fabricated from metal-insulator-superconductor (NIS) trilayer films by ozone assisted molecular beam epitaxy. The in situ reflection high-energy electron diffraction (RHEED) was used to characterize the surface crystal structure and morphology during film and heteroepitaxial barrier growth. A subgap asymmetry of the quasiparticle density of states in the superconducting state was observed as a consequence of the termination of the cuprate crystal at the boundary.
ASJC Scopus subject areas
- Physics and Astronomy(all)