Large anisotropic uniaxial pressure dependencies of Tc in single crystalline Ba(Fe0.92Co0.08)2As2.
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.
Hardy
Frédéric
F
Forschungszentrum Karlsruhe, Institut für Festkörperphysik, PO Box 3640, 76021 Karlsruhe, Germany.
Adelmann
Peter
P
Wolf
Thomas
T
V Löhneysen
Hilbert
H
Meingast
Christoph
C