Dresden 2011 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 10: Poster Session: Superconductivity

TT 10.11: Poster

Montag, 14. März 2011, 14:00–18:00, P4

Low temperature specific heat and thermal expansion measurements of Ba(Fe_1−xCo_x)₂As₂ single crystals in high magnetic fields — •Philipp Burger^1,2, Frédéric Hardy¹, Devang Joshi¹, Peter Adelmann¹, Doris Ernst¹, Rainer Fromknecht¹, Peter Schweiss¹, Thomas Wolf¹, and Christoph Meingast¹ — ¹Institut für Festkörperphysik, Karlsruher Institut für Technologie, 76021 Karlsruhe, Germany — ²Fakultät für Physik, Karlsruher Institut für Technologie, 76128 Karlsruhe, Germany

Low temperature specific heat and thermal expansion measurements have been performed on underdoped (T_c=12.7 K), optimally doped (T_c=24.5 K) and overdoped (T_c=9.1 K) Ba(Fe_1−xCo_x)₂As₂ single crystals in magnetic fields up to 14 T applied both parallel and perpendicular to the Fe layers. Whereas the specific heat anomalies in under- and over-doped crystals are significantly reduced in size by the magnetic field, the size of the thermal expansion anomalies are hardly affected by the field. The electronic Grüneisen parameters associated with the superconducting properties are calculated from the data and will be examined for signs of quantum criticality. Further, the anisotropy associated with the superconducting state, as well as the low temperature field dependence of the Sommerfeld coefficients will be discussed.