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TT: Fachverband Tiefe Temperaturen

TT 54: Focused Session: Magnetism & Superconductivity in Fe-based Pnictides and Chalcogenides (jointly with MA)

TT 54.3: Topical Talk

Donnerstag, 14. März 2013, 10:30–11:00, H20

A Light Scattering Study of the Evolution of Pairing in Fe-based Superconductors — •Rudi Hackl¹, Florian Kretzschmar¹, Bernhard Muschler¹, Thomas Böhm¹, Hai-Hu Wen², Vladimir Tsurkan^3,4, Joachim Deisenhofer³, and Alois Loidl³ — ¹Walther-Meissner-Institut, DE-85748 Garching — ²Nanjing University, Nanjing 210093, China — ³University of Augsburg, DE-86159 Augsburg — ⁴Academy of Sciences of Moldova, MD-2028 Chisinau

The iron-based superconductors are a laboratory for exploring the relevance of electron-electron interactions beyond electron-phonon coupling, being at work in conventional superconductors, since the Fermi surfaces can be varied systematically by atomic substitution. This enables one to systematically study magnetism and superconductivity as a function of the Fermi surface topology. Inelastic light scattering affords a window into the electronic properties of the ordered states. In particular, the evolution of the superconducting pairing upon doping can be probed since light scattering allows access to the anisotropy of the energy gap and, in some cases, of the pairing potential. Ba_1−xK_xFe₂As₂ is one of those cases since the competition between s- and d-wave pairing leads to the appearance of exciton-like modes below the gap edges of the various bands. Along with the results from other materials having different Fermi surface cross-sections the data in Ba_1−xK_xFe₂As₂ support the spin fluctuation scenario driven by interband coupling. The experiments show that there exist alternative routes for the analysis of the pairing interaction in superconductors with unconventional coupling and anisotropic gaps.