title: Angle-dependent evolution of the Fulde-Ferrell-Larkin-Ovchinnikov state in an organic superconductor.
abstract: We report magnetic-field and angular-dependent high-resolution specific-heat measurements of the organic superconductor β''-(BEDT-TTF)2SF5CH2CF2SO3. When the magnetic field is aligned precisely within the conducting BEDT-TTF layer, at low temperatures a clear upturn of the upper critical field beyond the Pauli limit of 9.73 T is observed, hinting at the emergence of a Fulde-Ferrell-Larkin-Ovchinnikov state. This upturn disappears when the field is oriented out of plane by more than ∼0.5  deg. For smaller out-of-plane angles, the specific-heat anomaly at T(c) sharpens and a second peaky phase transition appears within the superconducting state.
authors.affiliation: Hochfeld-Magnetlabor Dresden (HLD), Helmholtz-Zentrum Dresden-Rossendorf, D-01314 Dresden, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Beyer
authors.forename: B
authors.initials: B
authors.lastname: Bergk
authors.forename: S
authors.initials: S
authors.lastname: Yasin
authors.forename: J A
authors.initials: JA
authors.lastname: Schlueter
authors.forename: J
authors.initials: J
authors.lastname: Wosnitza