arXiv 0812.41762008-12-22cond-mat.supr-concond-mat.str-el

Large anisotropic uniaxial pressure dependencies of Tc in single crystalline Ba(Fe0.92Co0.08)2As2

Frederic Hardy, Peter Adelmann, Hilbert v. Loehneysen, Thomas Wolf, Christoph Meingast

备注：: 11 pages, 4 Figures
DOI：: 10.1103/PhysRevLett.102.187004

英文摘要：

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 of 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. A surprising similarity with the uniaxial pressure effects in several other layered superconductors is discussed.

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