Regensburg 2016 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 19: Superconductivity: Poster Session

TT 19.17: Poster

Monday, March 7, 2016, 15:00–18:00, Poster D

Electronic correlations in the superconductors AFe₂As₂ with A = K, Rb, and Cs — •Sebastian Kuntz¹, Felix Eilers¹, Kai Grube¹, Diego A. Zocco¹, Peter Schweiss¹, Rolf Heid¹, Thomas Wolf¹, Peter Adelmann¹, and Hilbert von Löhneysen^1,2 — ¹Karlsruhe Institute of Technology, Institut für Festkörperphysik, 76021 Karlsruhe, Germany — ²Karlsruhe Institute of Technology, Physikalisches Institut, 76131 Karlsruhe, Germany

The stoichiometric iron-pnictide superconductors AFe₂As₂ exhibit a diverging effective mass of the normal-conducting quasiparticles with increasing alkali-metal ion radius R_A. This divergence suggests the proximity to a quantum phase transition (QPT) at negative pressures. We have performed thermal expansion, magnetostriction and magnetization measurements to characterize the normal and superconducting properties. We determined the phase diagrams as a function of the magnetic field parallel and perpendicular to the c axis. The measurements reveal the presence of several bands. The quasi-two-dimensional electronic structure of these layered materials leads to a Pauli limitation of the superconductivity for fields perpendicular to the c axis. The influence of the nearby QPT will be discussed and compared with the behavior of other related Fe-based superconductors.