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TT: Fachverband Tiefe Temperaturen
TT 53: Superconductivity: Fe-based Superconductors - 122
TT 53.13: Talk
Wednesday, April 2, 2014, 12:45–13:00, HSZ 201
Measuring detwinned EuFe2As2 without external pressure — •Jannis Maiwald1, Christian Stingl1, Sina Zapf2, Shuai Jiang2, Nora Bach1, Kirk Post3, Hirale S. Jeevan1, David Neubauer2, Anja Löhle2, Conrad Clauss2, Dimitri Basov3, Martin Dressel2, and Philipp Gegenwart1 — 1I.Physikalisches Institut, Georg-August-Universität Göttingen, Germany — 21.Physikalisches Institut, Universität Stuttgart, Germany — 3Department of Physics, UC San Diego, USA
The formation of twin domains in the low temperature state of high-temperature superconductors is impeding the investigation of the in-plane anisotropy of these materials. Due to the applied pressure, mechanical clamps—commonly used to detwin crystals—induce artificial anisotropy and thus complicate the interpretation of acquired data. In case of the iron pnicides, application of typical laboratory magnetic fields did not lead to a substantial detwinning. In this talk we present a novel way to detwin EuFe2As2 by brief application of a small magnetic field of ∼ 1 Tesla. We will discuss magnetoresistance, magnetostriction/themal expansion and thermopower measurements, revealing that the Eu2+ moments support the detwinning not only below, but also above their magnetic ordering at 19K. After removing the field the system remains detwinned up to the structural and electronic phase transition at 190 K, providing a unique possibility to study the in-plane anisotropic properties of this material without the application of any external force.