Crossovers between superconducting symmetry classes
Abstract
We study the average density of states in a small metallic grain coupled to two superconductors with the phase difference π, in a magnetic field. The spectrum of the lowenergy excitations in the grain is described by the random matrix theory whose symmetry depends on the magnetic field strength and coupling to the superconductors. In the limiting cases, a pure superconducting symmetry class is realized. For intermediate magnetic fields or couplings to the superconductors, the system experiences a crossover between different symmetry classes. With the help of the supersymmetric σmodel we derive the exact expressions for the average density of states in the crossovers between the symmetry classes AC and CIC.
 Publication:

Soviet Journal of Experimental and Theoretical Physics Letters
 Pub Date:
 October 2011
 DOI:
 10.1134/S0021364011150057
 arXiv:
 arXiv:1106.3863
 Bibcode:
 2011JETPL..94..222K
 Keywords:

 Condensed Matter  Disordered Systems and Neural Networks;
 Condensed Matter  Mesoscale and Nanoscale Physics;
 Condensed Matter  Superconductivity;
 Mathematical Physics
 EPrint:
 6 pages