Regensburg 2013 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 27: Superconductivity: Fe-based Superconductors - 122

TT 27.6: Vortrag

Dienstag, 12. März 2013, 11:15–11:30, H18

Softening of the elastic shear mode C₆₆ in iron-based superconductors — •Anna Böhmer^1,2, Philipp Burger^1,2, Frédéric Hardy¹, Peter Schweiss¹, Rainer Fromknecht¹, Thomas Wolf¹, Christoph Meingast¹, Marius Reinecker³, and Wilfried Schranz³ — ¹Karlsruher Institut für Technologie, Institut für Festkörperphysik, D-76021 Karlsruhe — ²Karlsruher Institut für Technologie, Fakultät für Physik, D-76128 Karlsruhe — ³Universität Wien, Fakultät für Physik, A-1090 Wien

The structural phase transition of underdoped iron-based superconductors is accompanied by a large softening of the elastic shear mode C₆₆, which has attracted considerable attention. This softening has been discussed both in terms of orbital and spin-nematic fluctuations which would be responsible for the structural phase transition and, possibly, superconductivity. However, sample requirements have so far restricted experimental investigations of C₆₆ (via measurements of the ultrasound velocity) to the Ba(Fe,Co)₂As₂ system.

Here, we report on a new technique, based on a three-point bending setup, to probe the Young’s modulus of a sample with a capacitance dilatometer. For certain orientations, the Young’s modulus is related to the elastic constant C₆₆ whose effective temperature dependence can be obtained. Platelet-like samples, as frequently encountered for iron-based systems, are easily studied with our setup. Data on several systems will be presented and discussed.