Numéro |
J. Phys. I France
Volume 5, Numéro 12, December 1995
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Page(s) | 1577 - 1613 | |
DOI | https://doi.org/10.1051/jp1:1995219 |
J. Phys. I France 5 (1995) 1577-1613
Mean-Field Theory of a Quasi-One-Dimensional Superconductor in a High Magnetic Field
N. DupuisLaboratoire de Physique des Solides, Université Paris-Sud, 91405 Orsay, France
(Received 7 July 1995, accepted 5 September 1995)
Abstract
In a quasi-1D superconductor (weakly coupled chains system) with an open Fermi surface, a
high magnetic field stabilizes a cascade of superconducting phases wich ends in a strong reentrance
of the superconducting phase. The superconducting state evolves from a triangular Abrikosov vortex
lattice in the weak field regime towards a Josephson vortex lattice in the reentrant phase. We study
the properties of these superconducting phases from a microscopic model in the mean-field
approximation. The critical temperature is calculated in the quantum limit approximation (QLA) where
only Cooper logarithmic singularities are retained while less divergent terms are ignored. The
effects of Pauli pair breaking (PPB) and impurity scattering are taken into account. The Gor'kov
equations are solved in the same approximation but ignoring the PPB effect. We derive the GL
expansion of the free energy and obtain the specific heat jump at the transition. We show
that a gap opens at the Fermi level in the quasi-particle excitation spectrum. The QLA clearly shows
how the system evolves from a quasi-2D and BCS-like behavior in the reentrant phase toward a gapless
behavior at weaker field. The calculation is extended beyond the QLA whose validity is discussed in
detail.
© Les Editions de Physique 1995