Sharoni Amos, Asulin Itay, Koren Gad, Millo Oded
Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel.
Phys Rev Lett. 2004 Jan 9;92(1):017003. doi: 10.1103/PhysRevLett.92.017003. Epub 2004 Jan 8.
Scanning tunneling spectroscopy on gold layers overcoating c-axis YBa(2)Cu(3)O(7-delta) (YBCO) films reveals proximity-induced gap structures. The gap size reduces exponentially with the distance from a-axis facets, indicating that the proximity effect is primarily due to the (100) YBCO facets. The penetration depth of superconductivity into the gold is approximately 30 nm, in good agreement with estimations for the dirty limit. The extrapolated gap at the interface is approximately 15 meV, similar to the value of an s-wave component of the order parameter measured at the YBCO surface in recent point-contact experiments.
