title: Large anisotropic uniaxial pressure dependencies of Tc in single crystalline Ba(Fe0.92Co0.08)2As2.
abstract: Using high-resolution dilatometry, we study the thermodynamic response of the lattice parameters to superconducting order in a self-flux grown Ba(Fe0.92Co0.08)2As2 single crystal. The uniaxial-pressure dependencies of the critical temperature Tc calculated using our thermal-expansion and specific-heat data via the Ehrenfest relation, are found to be quite large and very anisotropic (dTc/dpa=3.1(1) K/GPa and dTc/dpc=-7.0(2) K/GPa). Our results show that there is a strong coupling of the c/a ratio to superconducting order, which demonstrates that Tc is far from the optimal value.
authors.affiliation: Forschungszentrum Karlsruhe, Institut für Festkörperphysik, PO Box 3640, 76021 Karlsruhe, Germany.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Hardy
authors.forename: Peter
authors.initials: P
authors.lastname: Adelmann
authors.forename: Thomas
authors.initials: T
authors.lastname: Wolf
authors.forename: Hilbert
authors.initials: H
authors.lastname: V Löhneysen
authors.forename: Christoph
authors.initials: C
authors.lastname: Meingast