Print Email Facebook Twitter Secondary “smile”-gap in the density of states of a diffusive Josephson junction for a wide range of contact types Title Secondary “smile”-gap in the density of states of a diffusive Josephson junction for a wide range of contact types Author Reutlinger, J. Glazman, L. Nazarov, Y.V. Belzig, W. Faculty Applied Sciences Department QN/Quantum Nanoscience Date 2014-07-31 Abstract The superconducting proximity effect leads to strong modifications of the local density of states in diffusive or chaotic cavity Josephson junctions, which displays a phase-dependent energy gap around the Fermi energy. The so-called minigap of the order of the Thouless energy ETh is related to the inverse dwell time in the diffusive region in the limit ETh??, where ? is the superconducting energy gap. In the opposite limit of a large Thouless energy ETh??, a small new feature has recently attracted attention, namely, the appearance of a further secondary gap, which is around two orders of magnitude smaller compared to the usual superconducting gap. It appears in a chaotic cavity just below the superconducting gap edge ? and vanishes for some value of the phase difference between the superconductors. We extend previous theory restricted to a normal cavity connected to two superconductors through ballistic contacts to a wider range of contact types. We show that the existence of the secondary gap is not limited to ballistic contacts, but is a more general property of such systems. Furthermore, we derive a criterion which directly relates the existence of a secondary gap to the presence of small transmission eigenvalues of the contacts. For generic continuous distributions of transmission eigenvalues of the contacts, no secondary gap exists, although we observe a singular behavior of the density of states at ?. Finally, we provide a simple one-dimensional scattering model which is able to explain the characteristic “smile” shape of the secondary gap. To reference this document use: http://resolver.tudelft.nl/uuid:accf092e-b6d5-4bae-a5c0-05ed687bd59a DOI https://doi.org/10.1103/PhysRevB.90.014521 Publisher American Physical Society Source http://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.014521 Source Physical Review B, 90, 2014 Part of collection Institutional Repository Document type journal article Rights © 2014 American Physical Society Files PDF Nazarov_2014.pdf 2.53 MB Close viewer /islandora/object/uuid:accf092e-b6d5-4bae-a5c0-05ed687bd59a/datastream/OBJ/view