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Proximity Effect in Gold Coated $YBa_2Ca_3O_{7-δ}$ Films Studied by Scanning Tunneling Spectroscopy

Amos Sharoni·Itay Asulin·Gad Koren·Oded Millo
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Abstract

Scanning tunneling spectroscopy on gold layers over-coating \textit{c}-axis $YBa_2Ca_3O_{7-δ}$ (YBCO) films reveals proximity induced gap structures. The gap size reduced exponentially with distance from \textit{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 $\sim 30$ nm, in good agreement with estimations for the dirty limit. The extrapolated gap at the interface is $\sim 15$ meV, consistent with recent point-contact experiments. The proximity-induced order parameter appears to have predominant \textit{s}-wave symmetry.

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Amos Sharoni, Itay Asulin, Gad Koren, Oded Millo. 2003-07-07. Proximity Effect in Gold Coated $YBa_2Ca_3O_{7-δ}$ Films Studied by Scanning Tunneling Spectroscopy. https://arxiv.org/abs/cond-mat/0307129

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