Regensburg 2010 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 20: SC: Fabrication and Characterization of Iron-Based and Other Superconductors

TT 20.6: Talk

Wednesday, March 24, 2010, 10:45–11:00, H19

Crystal growth and physical characterization of Ba(Fe_1−xCo_x)₂As₂ — •C. Nacke¹, G. Behr¹, S. Singh¹, N. Leps¹, G. Friemel¹, U. Stockert¹, H.H. Klauss², S. Wurmehl¹, C. Hess¹, R. Klingeler¹, and B. Büchner¹ — ¹Leibnitz Institute for Solid State and Material Research (IFW) Dresden, Germany — ²TU Dresden, Institute for Solid State Physics, Germany

The vertical Bridgman technique was used to grow mm-size crystals of the BaFe₂As₂ compound and its Co-doped superconducting variants. With this technique the crystals were grown directly from a stoichiometric melt with the composition Ba(Fe_1−xCo_x)₂As₂. The resulting crystals were platelet-like and have lateral sizes up to 10 x 10 mm² and a thickness up to 1 mm. Analysis by X-ray diffraction and EDX confirm the correct Ba-122-phase. Measurements of magnetic susceptibility and electrical resistivity reveal superconducting properties of the Co-doped crystals. The suceptibility plots for the 10% Co-doping samples (x=0.1) show a sharp transition to superconductivity at T_c=23 K. This data are in good agreement with those from the resistivity. In particular, the zero-field µSR data show a pure Gaussian relaxation and confirm very high sample purity.