title: Calorimetric evidence for a Fulde-Ferrell-Larkin-Ovchinnikov superconducting state in the layered organic superconductor kappa-(BEDT-TTF)2Cu(NCS)2.
abstract: The specific heat of the layered organic superconductor kappa-(BEDT-TTF)(2)Cu(NCS)(2), where BEDT-TTF is bisethylenedithio-tetrathiafulvalene, has been studied in magnetic fields up to 28 T applied perpendicular and parallel to the superconducting layers. In parallel fields above 21 T, the superconducting transition becomes first order, which signals that the Pauli-limiting field is reached. Instead of saturating at this field value, the upper-critical-field increases sharply and a second first-order transition line appears within the superconducting phase. Our results give strong evidence that the phase, which separates the homogeneous superconducting state from the normal state is a realization of a Fulde-Ferrell-Larkin-Ovchinnikov state.
authors.affiliation: Department of Condensed Matter Physics, University of Geneva, CH-1211 Geneva 4, Switzerland.
authors.forename: R
authors.initials: R
authors.lastname: Lortz
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: A
authors.initials: A
authors.lastname: Demuer
authors.forename: P H M
authors.initials: PH
authors.lastname: Böttger
authors.forename: B
authors.initials: B
authors.lastname: Bergk
authors.forename: G
authors.initials: G
authors.lastname: Zwicknagl
authors.forename: Y
authors.initials: Y
authors.lastname: Nakazawa
authors.forename: J
authors.initials: J
authors.lastname: Wosnitza