Microscopic theory of the Andreev gap.
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 tD<<tE, 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.
Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
Tobias
T
Micklitz
Alexander
A
Altland