title: Gapless Fermi surfaces of anisotropic multiband superconductors in a magnetic field.
abstract: We propose that a new state with a fully gapless Fermi surface appears in quasi-2D multiband superconductors in magnetic field applied parallel to the plane. It is characterized by a paramagnetic moment caused by a finite density of states on the open Fermi surface. We calculate thermodynamic and magnetic properties of the gapless state for both s-wave and d-wave cases, and discuss the details of the first order metamagnetic phase transition that accompanies the appearance of the new phase in s-wave superconductors. We suggest possible experiments to detect this state both in the s-wave (2-H NbSe2) and d-wave (CeCoIn5) superconductors.
authors.affiliation: Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996-1200, USA.
authors.forename: Victor
authors.initials: V
authors.lastname: Barzykin
authors.forename: L P
authors.initials: LP
authors.lastname: Gor'kov