Regensburg 2019 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 5: Superconductivity: Fe-based Superconductors - FeSe and 122

TT 5.11: Talk

Monday, April 1, 2019, 12:15–12:30, H23

Unusual thermoelectric properties of BaFe₂As₂ in high magnetic fields — •Martina Meinero^1,2, Federico Caglieris³, Gianrico Lamura², Ilaria Pallecchi², Andreas Jost⁴, Uli Zeitler⁴, Shigeyuki Ishida⁵, Hiroshi Eisaki⁵, and Marina Putti^1,2 — ¹Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146 Genova, Italy — ²CNR-SPIN, Corso Perrone 24, 16152 Genova, Italy — ³IFW Dresden, Helmholtz Strasse 33, Dresden, Germany — ⁴High Field Magnet Laboratory (HFML-EMFL), Radboud University, Toernooiveld 7, 6525ED Nijmegen, The Netherlands — ⁵National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8568, Japan

Electric and thermoelectric transport properties are mutually intertangled in diffusive transport equations. In particular, in high mobility multiband systems an anomalous behavior may occur, which can be tracked down to the properties of the individual bands. Here, we present magneto-electric and magneto-thermoelectric transport properties of a BaFe₂As₂ high-quality single crystal, for different magnetic field directions up to 30 T. We detect a giant Nernst effect and an anomalous field dependence of the Seebeck coefficient. The extraction of the Peltier tensor coefficients α_xx, α_xy and α_xz allows us to disentangle the main transport mechanisms in play. The large α_xy and α_xz values and their field dependence provide evidence of the presence of a high mobility band, compatible with a Dirac dispersion band, crossing the Fermi level, and suggest a possible three-dimensional nature of the Dirac fermions.