Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 27: Superconductivity: Fe-based Superconductors - 122
TT 27.7: Vortrag
Dienstag, 12. März 2013, 11:30–11:45, H18
Paramagnetic limiting of the upper critical field of KFe2As2 studied by low temperature thermal expansion and magnetostriction — •Diego A. Zocco1, Kai Grube1, Sebastian Zaum1, Felix Eilers1, Roland Schäfer1, Thomas Wolf1, Philipp Burger1, Frédéric Hardy1, Anna Böhmer1, Christoph Meingast1, and Hilbert von Löhneysen1,2 — 1Institut für Festkörperphysik, Karlsruhe Institute of Technology, D-76021 Karlsruhe, Germany — 2Physikalisches Institut, Karlsruhe Institute of Technology, D-76031 Karlsruhe, Germany.
We present low-temperature thermal expansion and magnetostriction measurements of single crystals of KFe2As2 (Tc ∼ 3.4 K) in magnetic fields up to 14 T applied parallel and perpendicular to the c-axis of the samples (Bc2c ∼ 1.5 T and Bc2ab ∼ 4.8 T). In the normal state, quantum oscillations of the sample length were observed for B∥ c and B⊥ c, giving estimated mean-free-path values of 177 and 52 nm, respectively, indicating that the superconducting state can be described as being in the clean limit (ξ0ab ∼ 10 nm). While the superconducting state is limited by orbital pair-breaking effects when magnetic fields are applied parallel to the c-axis, our measurements confirm strong paramagnetic effects on Bc2(T) along the ab direction, as it was similarly found in other Fe-based materials such as LiFeAs and FeSe1−xTex.