Volume 82, Number 4, May 2008
|Number of page(s)||6|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||08 May 2008|
Decreasing excitation gap in Andreev billiards by disorder scattering
Institute for Theoretical Physics, Vienna University of Technology - A-1040 Vienna, Austria, EU
2 Department of Applied Physics, Yale University - New Haven, CT 06520, USA
3 Department of Physics, University of Wisconsin - Madison, WI 53706, USA
Corresponding author: firstname.lastname@example.org
Accepted: 27 March 2008
We investigate the distribution of the lowest-lying energy states in a disordered Andreev billiard by solving the Bogoliubov-de Gennes equation numerically. Contrary to conventional predictions we find a decrease rather than an increase of the excitation gap relative to its clean ballistic limit. We relate this finding to the eigenvalue spectrum of the Wigner-Smith time delay matrix between successive Andreev reflections. We show that the longest rather than the mean time delay determines the size of the excitation gap. With increasing disorder strength the values of the longest delay times increase, thereby, in turn, reducing the excitation gap.
PACS: 74.45.+c – Proximity effects; Andreev effect; SN and SNS junctions / 73.21.La – Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems: Quantum dots / 05.45.Mt – Quantum chaos; semiclassical methods
© EPLA, 2008
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.