Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 30: Superconductivity: Fe-based Superconductors - Theory

TT 30.5: Vortrag

Dienstag, 8. März 2016, 12:15–12:30, H19

Robust Determination of the Superconducting Gap Sign Structure via Quasiparticle Interference — •Dustin Altenfeld¹, Peter Hirschfeld², Ilya Eremin^1,3, and Igor Mazin⁴ — ¹Institut für Theoretische Physik III, Ruhr-Universität Bochum, D-44801 Bochum, Germany — ²Department of Physics, University of Florida, Gainesville, Florida 32611, USA — ³Kazan Federal University, Kazan 420008, Russian Federation — ⁴Code 6393, Naval Research Laboratory, Washington, DC 20375, USA

Using an electronic theory, we present a qualitative description to identify sign changes of the superconducting order parameter via quasiparticle interference (QPI) measurement in Fe-based superconductors (FeSc). In particular, we point out that the temperature dependence of the momentum-integrated QPI data can be used to differentiate between s₊₋ and s₊₊ states in a system with typical iron pnictide Fermi surface. We show that the signed symmetrized and antisymmetrized QPI maps are useful to obtain a characteristic signature of a gap sign change or lack thereof, starting from two-band model up to ab initio based band structure calculation. We further suggest this method as a robust way of the determination of the superconducting gap sign structure in experiment and discuss its application to the LiFeAs compounds.