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 20.4: Talk

Wednesday, March 24, 2010, 10:15–10:30, H19

Phase diagram of Ca(Fe_1−xCo_x)₂As₂ — •Ulrike Stockert, Mahmoud Abdel-Hafez, Luminita Harnagea, Surjeet Singh, Norman Leps, Liran Wang, Gerd Friemel, Sabine Wurmehl, Günter Behr, Christian Hess, Rüdiger Klingeler, and Bernd Büchner — Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Germany

We report on magnetic and thermodynamic measurements on Ca(Fe_1−xCo_x)₂As₂ (0≤ x ≤0.2) single crystals grown from Sn-flux. Upon Co substitution, the first-order structural/magnetic phase transition of CaFe₂As₂ is split and shifted to lower temperatures. Simultaneously, superconductivity evolves at low T. The superconducting volume fraction depends sensitively on the Co content and reaches 100 % only above the optimum doping level of x ∼ 0.065, as the magnetic and structural transitions are completely suppressed. We discuss the phase diagram of Ca(Fe_1−xCo_x)₂As₂ in consideration of recent investigations of CaFe₂As₂ under pressure, which revealed a sensitive pressure dependence of the structural/magnetic phase transitions and a T_c as high as 10 K at 3.5 kbar.