"Smile"-gap in the density of states of a cavity between superconductors

Abstract

The density of Andreev levels in a normal metal ($N$) in contact with two superconductors ($S$) is known to exhibit an induced minigap related to the inverse dwell time. We predict a small secondary gap just below the superconducting gap edge---a feature that has been overlooked so far in numerous studies of the density of states in $S-N-S$ structures. In a generic structure with $N$ being a chaotic cavity, the secondary gap is the widest at zero phase bias. It closes at some finite phase bias, forming the shape of a "smile". Asymmetric couplings give even richer gap structures near the phase difference π. All the features found should be amendable to experimental detection in high-resolution low-temperature tunneling spectroscopy.

arXiv comment5 pages, 4 figures

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Cited by in corpus (7)

• Closing the proximity gap in a metallic Josephson junction between three superconductors
• Proximity nanovalve with large phase-tunable thermal conductance
• Order, disorder and tunable gaps in the spectrum of Andreev bound states in a multi-terminal superconducting device
• Josephson currents in chaotic quantum dots
• Secondary "Smile"-gap in the density of states of a diffusive Josephson junction for a wide range of contact types
• Mesoscopic fluctuations in superconductor-topological insulator Josephson junctions
• Peculiarities of the density of states in SN junctions