Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 21: Superconductivity: Poster Session

TT 21.18: Poster

Montag, 16. März 2015, 15:00–18:00, Poster B

Persistent detwinning of EuFe₂As₂ by small magnetic fields — •Jannis Maiwald¹, Christian Stingl¹, Sina Zapf², Shuai Jiang², Nora Bach¹, Kirk Post³, H. S. Jeevan¹, David Neubauer², Anja Löhle², Conrad Clauss², Dimitri Basov³, Martin Dressel², and Philipp Gegenwart¹ — ¹Experimentalphysik VI, Universität Augsburg, Germany — ²1.Physikalisches Institut, Universität Stuttgart, Germany — ³Department of Physics, UC San Diego, USA

The formation of twin domains in the orthorhombic phase of high-temperature superconductors is impeding the investigation of the in-plane anisotropy of these materials. Recently, we have shown how the brief application of a small magnetic field of ∼ 1 Tesla in the EuFe₂As₂ iron pnictide leads to a substantial detwinning of the system, which is persistent up to the structural transition at ∼ 190 K even after the magnetic field has been switched off. This offers researchers the opportunity to investigate the detwinned iron arsenide without the application of any external symmetry breaking force, like the pressure of a mechanical clamp, or a magnetic field present during measurement. We will present angular dependent magnetoresistance, magnetostriction, thermal expansion and thermoelectric power measurements on the EuFe₂As₂ parent compound as well as on various doped variants in order to shed further light on the mechanism behind the field induced detwinning, i.e. the interplay of the involved magnetic moments stemming form the Eu and Fe atoms in these compounds.