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Phys. Rev. Lett. 103, 080403 (2009) [4 pages]

Microscopic Theory of the Andreev Gap

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Tobias Micklitz1 and Alexander Altland2
1Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
2Institut für Theoretische Physik, Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany

Received 12 February 2009; published 20 August 2009

We present a microscopic theory of the Andreev gap, i.e., the phenomenon that the density of states (DOS) of normal chaotic cavities attached to superconductors displays a hard gap centered around the Fermi energy. Our approach is based on a solution of the quantum Eilenberger equation in the regime tDtE, where tD and tE are the classical dwell time and Ehrenfest time, respectively. We show how quantum fluctuations eradicate the DOS at low energies and compute the profile of the gap to leading order in the parameter tD/tE.

© 2009 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.103.080403
DOI:
10.1103/PhysRevLett.103.080403
PACS:
03.65.Sq, 03.65.Yz, 05.45.Mt