Berlin 2015 – wissenschaftliches Programm
TT 21.15: Poster
Montag, 16. März 2015, 15:00–18:00, Poster B
Electronic correlations in the superconductors AFe2As2 with A = K, Rb, and Cs — •Kai Grube1, Felix Eilers1, Diego A. Zocco1, Peter Schweiss1, Rolf Heid1, Thomas Wolf1, and Hilbert von Löhneysen1,2 — 1Karlsruhe Institute of Technology, Institut für Festkörperphysik, 76021 Karlsruhe, Germany — 2Karlsruhe Institute of Technology, Physikalisches Institut, 76131 Karlsruhe, Germany
Superconductivity in iron pnictides and chalcogenides occurs in the proximity to antiferromagnetic order, giving rise to the assumption that the superconductivity is unconventional and originates from electron-electron interactions. So far, experimental and theoretical studies underpin this assumption but fail to unravel the pairing mechanism. A central question is the role of electronic correlations in these materials. We have investigated the thermal expansion and magnetostriction of the stoichiometric compounds AFe2As2 with A = K, Rb, and Cs. Our measurements show a huge increase of the effective mass quasiparticles meff with increasing A ion radius, while the superconducting transition temperature Tc decreases. The relation between superconductivity and electronic correlations will be discussed by using the uniaxial pressure dependences of Tc and meff and the temperature dependence of the upper critical field.