Anomalous density of states in a metallic film in proximity with a superconductor

Abstract

We investigated the local electronic density of states in superconductor-normal metal (Nb-Au) bilayers using a very low temperature (60 mK) STM. High resolution tunneling spectra measured on the normal metal (Au) surface show a clear proximity effect with an energy gap of reduced amplitude compared to the bulk superconductor (Nb) gap. Within this mini-gap, the density of states does not reach zero and shows clear sub-gap features. We show that the experimental spectra cannot be described with the well-established Usadel equations from the quasi-classical theory.

4 pages, 5 figures

References in corpus (9)

• Local Density of States in a Dirty Normal Metal connected to a Superconductor
• Induced superconductivity distinguishes chaotic from integrable billiards
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• Angle dependence of Andreev scattering at semiconductor-superconductor interfaces
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• A very low temperature STM for the local spectroscopy of mesoscopic structures
• The excitation spectrum of mesoscopic proximity structures
• Local spectroscopy of a proximity superconductor at very low temperature
• Spatially resolved spectroscopy on a superconducting proximity structure

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