Specific-heat discontinuity in impure two-band superconductors
Abstract
The Ginzburg-Landau coefficients and the jump of the specific heat are calculated for a disordered two-band superconductor. We start with the analysis of a more general case with arbitrary anisotropy. While the specific-heat discontinuity at the critical temperature Tc decreases with increasing disorder, its ratio to the normal-state specific heat at Tc increases and slowly converges to the isotropic value. For strong disorder the deviation from the isotropic value is proportional to the elastic electron-scattering time. In the case of a two-band superconductor we apply a simplified model of the interaction independent of the momentum within a band. In the framework of this model all thermodynamic variables can be found explicitly at any value of the scattering rate. This solution explains the sample dependence of the specific-heat discontinuity in MgB2 and the influence of disorder on the critical temperature.
- Publication:
-
Physical Review B
- Pub Date:
- September 2003
- DOI:
- 10.1103/PhysRevB.68.104517
- arXiv:
- arXiv:cond-mat/0209342
- Bibcode:
- 2003PhRvB..68j4517M
- Keywords:
-
- 74.20.Fg;
- 74.72.-h;
- BCS theory and its development;
- Cuprate superconductors;
- Condensed Matter - Superconductivity
- E-Print:
- New results relate to two-band superconductors, 9 pages, 2 figures