Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 53: Superconductivity: Fe-based Superconductors - 122
TT 53.1: Vortrag
Mittwoch, 2. April 2014, 09:30–09:45, HSZ 201
The Pauli-limited multiband superconductor RbFe2As2 — •Felix Eilers, Diego A. Zocco, Thomas Wolf, Peter Schweiss, Kai Grube, and Hilbert v. Löhneysen — Karlsruher Institut für Technologie, Institut für Festkörperphysik, Karlsruhe, Germany
The compounds AFe2As2 - where A denotes an alkali metal element like K or Rb - offer the possibility to probe the unconventional superconductivity in iron pnictides. The upper critical magnetic fields Hc2 are easily accessible and no additional chemical disorder is introduced by substitutional atoms. We measured the thermal expansion and magnetostriction of a RbFe2As2 single crystal at temperatures T between 50 mK and 4 K and magnetic fields µ0H up to 14 T. The quantum oscillations observed in our magnetostriction measurements indicate a strongly correlated electron system in accordance with the enhanced Sommerfeld coefficient and Pauli susceptibility of KFe2As2 [1]. In addition, they reveal, together with the thermal expansion, the multiband character of the electronic structure and superconductivity. The T-H phase diagram constructed from our field-dependent measurements shows the typical behavior of an orbitally limited superconductor for H parallel to the c-axis, while for H within the ab-plane the superconducting phase transition becomes discontinuous below T = 1.2 K. For this field direction the orbital limit strongly exceeds Hc2(T = 0), thus pointing to a Pauli-limited upper critical field like in KFe2As2 [2].
F. Hardy et al., PRL 111, 027002 (2013)
D. A. Zocco et al., PRL 111, 057007 (2013)