QUASI-ONE-DIMENSIONAL SUPERCONDUCTORS IN STRONG MAGNETIC-FIELD

We determine the phase diagram of a quasi-one-dimensional conductor (weakly coupled chains system with an open Fermi surface) in a magnetic field. The usual Ginzburg-Landau regime is followed, when the field is increased, by a cascade of superconducting phases separated by first order transitions, which ends with a strong reentrance of the super-conducting phase. These new phases show a novel kind of symmetry of laminar type. The Zeeman splitting does not completely suppress the reentrance in very strongfield, the ground state being in this case a Larkin-Ovchinnikov-Fulde-Ferrell state.