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TT: Fachverband Tiefe Temperaturen

TT 98: Poster Session: Superconductivity

TT 98.16: Poster

Donnerstag, 15. März 2018, 15:00–19:00, Poster B

Nernst effect of Rh-doped BaFe₂As₂: Evidence for superconductivity driven by nematic fluctuations — •Christoph Wuttke¹, Frank Steckel¹, Federico Caglieris¹, Steffen Sykora¹, Xiaochen Hong¹, Seunghyun Kim¹, Sabine Wurmehl¹, Sheng Ran², Paul C. Canfield², Bernd Büchner^1,3,4, and Christian Hess^1,4 — ¹Leibniz-Institute for Solid State and Materials Research, IFW-Dresden, 01069 Dresden, Germany — ²Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA — ³Institut für Festkörperphysik, TU Dresden, 01069 Dresden, Germany — ⁴Center for Transport and Devices, Technische Universität Dresden, 01069 Dresden, Germany

The nematic phase of iron-based superconductors is a very debated topic since the role of nematic fluctuations in the appearance of high temperature superconductivity is still controversial. In this work we systematically investigate the phase diagram of BaFe₂As₂ as a function of Rh-doping through Nernst effect measurements. In particular we obtained an anomalously high Nernst coefficient in the tetragonal phase. Moreover, we observe, that upon doping its magnitude strikingly mimics the shape of the superconducting dome. Using a minimal orbital model for iron-based superconductors we show that the Nernst coefficient couples directly to the nematic fluctuations. Our experimental results therefore provide direct evidence for nematic fluctuations playing a crucial role for the mechanism of superconductivity in Rh-doped BaFe₂As₂. We discuss our findings using a comparison with the nematic susceptibility obtained from elastoresistance measurements.