Dresden 2017 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 59: Superconductivity: Fe-based Superconductors - FeSe and others
TT 59.7: Vortrag
Donnerstag, 23. März 2017, 11:15–11:30, HSZ 103
Resonant scattering in the quasiparticle interference in superconducting LiFeAs — •Steffen Sykora1, Zhixiang Sun1, Pranab Kumar Nag1, Jose Maria Guevara Parra1, Danny Baumann1, Rhea Kappenberger1, Robert Beck1, Sabine Wurmehl1,2, Sergey Borisenko1, Bernd Büchner1,2,3, and Christian Hess1,3 — 1IFW Dresden — 2Institute for Solid State Physics, TU Dresden — 3Center for Transport and Devices, TU Dresden
Probing the quasiparticle interference (QPI) by scanning tunneling microscopy/spectroscopy (STM) is an important tool to investigate the character of the superconducting state. We develop a theoretical model for the QPI in LiFeAs and compare the results with recent STM measurements of the Fourier transformed local density of states. Our selfconsistent t-matrix calculation goes beyond the standard Born approximation and is based on realistic band structure data. We find dominant QPI intensity at small transfer momentum in excellent agreement with the experiment. An unusual measured in-gap intensity is explained within the same theoretical framework by higher-order Andreev-scattering processes. The theoretical analysis reveals an important role of specific multiple scattering processes that lead to a resonant scattering mode at the energy scale of the superconducting gap. We discuss our results in the context of the pairing mechanism in LiFeAs.