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TT: Fachverband Tiefe Temperaturen
TT 53: Superconductivity: Fe-based Superconductors - 122
TT 53.14: Talk
Wednesday, April 2, 2014, 13:00–13:15, HSZ 201
Permanent Detwinning of EuFe2As2 by indirect magnetoelastic coupling — •Sina Zapf1, Christian Stingl2, Kirk Post3, Jannis Maiwald2, Shuai Jiang1, Hirale S. Jeevan2, Nora Bach2, David Neubauer1, Anja Löhle1, Conrad Clauss1, Dimitri N. Basov3, Philipp Gegenwart2, and Martin Dressel1 — 11. Physikalisches Institut, Uni Stuttgart, Germany — 2I. Physikalisches Institut, Uni Göttingen, Göttingen — 3Department of Physics, UC San Diego, USA
In order to examine the in-plane anisotropy of high-temperature superconductors, sophisticated methods had to be developed for detwinning single crystals. Unfortunately, in the case of iron pnictides, typical laboratory magnetic fields do not yield an imbalance of twin domains by more than a few percent. Here we present a novel way of permanently detwinning EuFe2As2 single cystals in magnetic fields of less than 1 Tesla. We will discuss magneto-optical and magnetization measurements, revealing that the Eu2+ moments actually support the detwinning not only below, but also above their magnetic ordering at 19 K, probably by an indirect magnetoelastic coupling via the Fe2+ spins. Most strikingly, the detwinning remains even when the magnetic field is switched off and the resulting ratio of unbalanced twin domains of about 1:3 is robust against heating to the structural and electronic phase transition at 190 K. This provides a unique possibility to study the low temperature in-plane anisotropy of iron pnictides without the application of any external force, suitable for a wide variety of experimental techniques.