Regensburg 2010 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 9: SC: Poster Session

TT 9.29: Poster

Monday, March 22, 2010, 14:00–18:00, Poster A

Superconductivity and magnetism in Eu_1−xK_xFe₂(As_1−yP_y)₂ — •Jannis Maiwald, Hirale S. Jeevan, and Philipp Gegenwart — 1. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich Hund Platz 1, 37077 Göttingen, Germany

We report on a detailed investigation of superconductivity and magnetism in EuFe₂As₂ by doping of K and P. In this new class of FeAs-based superconductors it is found that superconductivity appears close to a magnetic instability, suggesting a possible unconventional pairing mechanism.
We have synthesized single crystals and powder samples of both doped and undoped samples of EuFe₂As₂ and investigated their physical properties, by means of heat capacity, resistivity, magnetization, thermal conductivity and seebeck-coefficient measurements. The parent compound shows an antiferromagnetic spin-density-wave accompanied by a structural transition (T_SDW) at ≈190K related to the Fe₂As₂ layers and magnetic ordering of Eu²⁺ (T_N) moments at ≈20K. Upon doping Eu with K >30%, T_SDW and T_N get suppressed and superconductivity appears at ≈32K. On the other hand P doping to the As site also suppresses the SDW transition and leads to a superconducting phase. However in the latter case the Eu transition temperature remains undisturbed. With further increased P doping the Eu order changes from AFM to FM. We will mainly discuss the thermal conductivity measurements of P and K doped samples.