Anomalous proximity effect in gold coated (110) $YB{a}_{2}C{u}_3{O}_{7-\delta }$ films: Penetration of the Andreev bound states

Abstract

Scanning tunneling spectroscopy of (110) $YB{a}_{2}C{u}_3{O}_{7-\delta }/Au$ bi-layers reveal a proximity effect markedly different from the conventional one. While proximity-induced mini-gaps rarely appear in the Au layer, the Andreev bound states clearly penetrate into the metal. Zero bias conductance peaks are measured on Au layers thinner than 7 nm with magnitude similar to those detected on the bare superconductor films. The peaks then decay abruptly with Au thickness and disappear above 10 nm. This length is shorter than the normal coherence length and corresponds to the (ballistic) mean free path.

arXiv comment5 prl format pages, 4 figures, to be published in PRL

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• Local Density of States in a Dirty Normal Metal connected to a Superconductor
• Circuit theory of unconventional superconductor junctions
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• Scanning tunneling spectroscopy of SmFeAsO0.85: Possible evidence for d-wave order parameter symmetry
• Proximity effect with noncentrosymmetric superconductors
• Evidence for Crossed Andreev Reflections in bilayers of (100)YBCO and the itinerant ferromagnet SrRuO3
• Superconducting proximity effects in metals with a repulsive pairing interaction
• Penetration of Andreev bound states into the ferromagnet in a SrRuO${}_3$/(110)YBa${}_2$Cu${}_3$O${}_{7-\delta }$ bilayer: a scanning tunneling spectroscopy study
• Scanning tunneling spectroscopy characterization of the pseudogap and the x = 1/8 anomaly in La2-xSrxCuO4 thin films
• Smearing origin of zero-bias conductance peak in Ag-SiO-Bi-2212 planar tunnel junctions: influence of diffusive normal metal verified with the circuit theory