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TT: Fachverband Tiefe Temperaturen

TT 5: Postersession Superconductivity: Materials - Fabrication and Properties

TT 5.29: Poster

Montag, 23. März 2009, 13:00–16:45, P1A

Crystal growth and sample-dependent physical properties of new superconducting SrFe_2−xM_xAs₂ (M = transition metal) compounds — •Andreas Leithe-Jasper, Walter Schnelle, Helge Rosner, and Ulrich Burkhardt — MPI für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, 01187 Dresden, Germany

We have recently reported about superconductivity with T_c up to 20 K in Co-substituted SrFe₂As₂ polycrystalline samples [1]. Here, electron-doping of the FeAs layers was accomplished by direct substitution of the transition metal. It was found that sample preparation and distribution of impurity phases influences the observed physical properties in a subtle way. The temperature dependence of the electrical conductivity as well magnetic susceptibility (superconducting parameters, magnetic secondary phases, homogeneity) and specific heat capacity will be presented and discussed. Crystals have been grown by a modified self-flux technique and the distribution of transition-metal dopants has been investigated by electron microprobe analysis. A comparison of the observed features with polycrystalline samples will be given. In addition, the possibility of complementary direct hole-doping has been explored.

[1] A. Leithe-Jasper, W. Schnelle, C. Geibel, H. Rosner, Phys. Rev. Lett. 101, 207004 (2008).