Regensburg 2019 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 49: Poster Session: Superconductivity

TT 49.17: Poster

Wednesday, April 3, 2019, 15:00–18:30, Poster D

Fermi-surface topology of (Rb,Cs)Fe₂As₂ — •Tobias Förster¹, Johannes Klotz¹, Seunghyun Khim², Saicharan Aswartham³, Helge Rosner², Ilya Sheikin⁴, and Jochen Wosnitza¹ — ¹Dresden High Magnetic Field Laboratory (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Germany — ²Max Planck Institute for Chemical Physics of Solids, Dresden, Germany — ³Leibniz Institute for Solid State and Materials Research (IFW), Dresden Germany — ⁴Laboratoire National des Champs Magnétiques Intenses (LNCMI-EMFL), Grenoble, France

The unique Fermi-surface topology of many iron-pnictide superconductors stimulates a number of theories on the nature of the pairing interactions in these materials. In the case of (K,Rb,Cs)Fe₂As₂, there is an ongoing discussion whether a Lifshitz transition is connected to the superconducting properties of these 122 iron arsenides. Studies of the pressure dependence of H_c2 did not find evidence for that kind of transition [1]. In contrast, high-resolution band-structure calculations show a van Hove singularity close to the Fermi energy, favoring a Lifshitz transition. In order to investigate the possible impact of this feature, a precise knowledge of the electronic structure is eminent. We, therefore, calculated the Fermi surface in (Rb,Cs)Fe₂As₂ and investigated the de Haas-van Alphen effect of (Rb,Cs)Fe₂As₂ in static fields up to 38 T. In our contribution, we show the results of our torque-magnetometry measurements and use them to refine band-structure calculations.

[1] F. F. Tafti et al., Phys. Rev. B. 89, 134502 (2014).