Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 8: Superconductivity - Poster Session

TT 8.6: Poster

Montag, 26. März 2007, 14:00–17:45, Poster A

Thermal Conductivity of underdoped YBa₂Cu₃O_y — •Robert Schneider¹, Anja Waske¹, Christian Hess¹, Bernd Büchner¹, Vladimir Hinkov², and Chengtian Lin² — ¹Leibniz-Institute for Solid State and Materials Research, IFW-Dresden, 01171 Dresden, Germany — ²Max Planck Institute for Solid State Research, Heisenbergstrae 1, D-70569 Stuttgart, Germany

We present experimental results on the thermal conductivity κ of an untwinned, underdoped YBa₂Cu₃O_y monocrystal along the ’a direction’ with a critical temperature of T_c = 61 K. We observe a peak at low temperatures as it has been previously found for the optimally doped material, for which it is known that the peak originates from heat transport by electronic quasiparticles. However, unlike for this latter case we do not observe a sharp onset of the peak at T_c but find a continuous increase already below T≈150 K. This increase becomes steeper at T_c and κ eventually peaks around 30 K. A magnetic field perpendicular to the CuO₂ planes significantly suppresses κ in the superconducting phase.