Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 34: Superconductivity: Heterostructures
TT 34.5: Vortrag
Dienstag, 1. April 2014, 12:30–12:45, HSZ 201
Multiply gapped density of states in a chaotic normal metal in contact with superconductors — •Johannes Reutlinger1, Wolfgang Belzig1, Yuli Nazarov2, and Leonid Glazman3 — 1University of Konstanz, Department of Physics, 78457 Konstanz, Germany — 2Kavli Institute of Nanoscience Delft, Delft University of Technology, 2628 CJ Delft, Netherlands — 3Department of Physics, Yale University, New Haven CT 06511-8499, USA
The spectral properties of a normal metal adjacent to a superconductor are strongly dependent on the characteristic mesoscopic energy scale - the Thouless energy ETh - and the strength of the connection. We predict that the local density of states (LDOS), besides the well known minigap ∼ ETh, can exhibit a multiple gap structure. For ballistic contacts we calculate these secondary gaps analytically in the framework of the quantum circuit theory of mesoscopic transport. For a cavity coupled to two superconductors with phase difference ϕ the secondary gap ∼ Δ3/ETh2 for ETh ≫ Δ with maximum width at ϕ=0 disappears at a critical phase ± Δ/ETh. The existence of a critical ratio ETh/Δ calls for a reconsideration of the level statistics in chaotic Andreev dynamics, which has previously only been addressed thoroughly for ETh ≪ Δ. For generic contacts, like diffusive connectors or dirty interfaces no gap exists, but the density of states is still suppressed around Δ. Analytical calculations relate the secondary gap to the transmission eigenvalue distribution at small transmissions.
J. Reutlinger, L. Glazman, Yu. V. Nazarov, W. Belzig, arXiv:1308.2529 (2013)