Dresden 2017 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 53: Poster Session: Superconductivity 1

TT 53.21: Poster

Mittwoch, 22. März 2017, 15:00–19:00, P2-OG2

Constraints on the total coupling strength to bosons in the Fe based superconductors — •Stefan-Ludwig Drechsler1, Helge Rosner2, Vadim Grinenko3, and Steve Johnston1,41Leibniz-Institute IFW-Dresden, D-01171 dresden, Germany — 2Max-Planck Institute f. Chemical Physics of Solids, Dresden, Germany — 3TU Dresden, Dresden, Germany — 4Deptm. of Physics and Astronomy, University of Tennesee, Knoxville 37996, USA

There is still no consistent interpretation of the normal state of Fe based superconductors (FeSC) properties, where the strength of the el-el interaction and the role of correlation effects are under debate. Based on empirical observations and qualitative insight from DFT calculations, we show that the superconducting and low-energy thermodynamic properties of the FeSC can be described semi-quantitively within multiband Eliashberg-theory. An important high-energy mass renormalization (MR) is accounted for phenomenologically in accord with constraints provided by thermodynamic, optical, and angle-resolved photoemission data. When viewed in this way, all FeSC with Tc < 40 K studied so far are found to belong to an intermediate coupling regime. This is in contrast to strong coupling scenarios proposed in the early period of the FeSC history. We also discuss several related issues, including the role of band shifts as measured by the positions of van Hove singularities, and a recently suggested a quantum critical point in the strongly hole-doped systems AFe2As2 (A = K, Rb, Cs). Using high-precision full relativistic GGA-band structure calculations, we arrive at a somewhat milder MR in comparison with other studies.

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