Dimer Impurity Scattering, "Reconstructed" Nesting and Density-Wave Diagnostics in Iron Pnictides

Abstract

While the impurity-induced nanoscale electronic disorder has been extensively reported in the underdoped iron pnictides, its microscopic origins remain elusive. Recent scanning tunneling microscopy (STM) measurements reveal a dimer-type resonant structure induced by cobalt doping. These dimers are randomly distributed but uniformly aligned with the antiferromagnetic a axis. A theory of the impurity-induced quasiparticle interference patterns is presented that shows the local density of states developing an oscillatory pattern characterized by both geometry and orbital content of the {\em reconstructed} Fermi pockets, occasioned by the pocket density-wave (PoDW) order along the b axis. This pattern breaks the $C_4$ symmetry and its size and orientation compare well with the dimer resonances found in the STM experiments, hinting at the presence of a "hidden" PoDW order. More broadly, our theory spotlights such nanoscale structures as a useful diagnostic tool for various forms of order in iron pnictides.

5 pages, 6 figures, published version

References in corpus (8)

• Superconductivity at 38 K in the iron arsenide (Ba1-xKx)Fe2As2
• High-temperature superconductivity in iron-based materials
• Evidence for an electron nematic phase transition in underdoped iron pnictide superconductors
• Multiband magnetism and superconductivity in Fe-based compounds
• Phase transitions in LaFeAsO: structural, magnetic, elastic, and transport properties, heat capacity and Mossbauer spectra
• Origin of Gap Anisotropy in Spin Fluctuation Models of the Fe-pnictides
• Effects of cobalt doping and three-dimensionality in $BaF{e}_{2}A{s}_2$
• Theory of Valley-Density Wave and Hidden Order in Iron-Pnictides