Thermodynamics and excitation spectrum of a quasi-one-dimensional superconductor in a high magnetic field.

Abstract

At high magnetic field, the semiclassical approximation which underlies the Ginzburg-Landau theory of the mixed state of type II superconductors breaks down. In a quasi-1D superconductor with an {\it open Fermi surface}, a high magnetic field stabilizes a cascade of superconducting phases which ends in a strong reentrance of the superconducting phase. From a microscopic mean-field model, we determine the thermodynamics and the excitation spectrum of these quantum superconducting phases.