Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 5: Superconductivity: Fe-based Superconductors - FeSe and 122

TT 5.5: Vortrag

Montag, 1. April 2019, 10:30–10:45, H23

Magnetic fluctuations in FeSe: effect of orbital selectivity — •Andreas Kreisel1, Johannes H. J. Martiny2, Brian M. Andersen3, and Peter J. Hirschfeld41Universität Leipzig, Germany — 2Center for Nanostructured Graphene, Technical University of Denmark, Denmark — 3Niels Bohr Institute, University of Copenhagen, Denmark — 4University of Florida, USA

Recent STM experiments and theoretical considerations have highlighted the role of interaction-driven orbital selectivity in FeSe, and its role in generating the extremely anisotropic superconducting gap structure in this material. We study the magnetic excitation spectrum resulting from the coherent quasiparticles within the same renormalized random phase approximation approach used to explain the STM experiments, and show that it agrees well with the low-energy momentum and energy dependent response measured by inelastic neutron scattering experiments. We find a correlation-induced suppression of (π,π) scattering due to a small quasiparticle weight of states of dxy character [1]. We compare predictions for twinned and untwinned crystals, and predict in particular a strongly (π,0)-dominated susceptibility at low energies in untwinned systems. Since the system is known to be close to a magnetic phase transition, it is possible that impurities can pin local magnetic order in this system. Within a mean field approach in real space, we deduce the structure of such local magnetic order and predict implications of this as been visible in a STM experiment even if a non-spinpolarized technique is used [2].
A. Kreisel et al., arXiv:1807.09482
J. Martiny et al., arXiv:1811.01788

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