Microscopic nature of correlations in multiorbital AFe2As2 (A=K,Rb,Cs): Hund's coupling versus Coulomb repulsion

Steffen Backes, Harald O. Jeschke, Roser Valentí

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41 Citations (Scopus)


We investigate via LDA+DMFT (local density approximation combined with dynamical mean field theory) the manifestation of correlation effects in a wide range of binding energies in the hole-doped family of Fe pnictides AFe2As2 (A=K,Rb, Cs) as well as the fictitious FrFe2As2 and a-axis stretched CsFe2As2. This choice of systems allows for a systematic analysis of the interplay of Hund's coupling JH and on-site Coulomb repulsion U in multiorbital Fe pnictides under negative pressure. With increasing ionic size of the alkali metal, we observe a nontrivial change in the iron 3d hoppings, an increase of orbitally-selective correlations, and the presence of incoherent weight at high binding energies that do not show the typical lower Hubbard-band behavior but rather characteristic features of a Hund's metal. This is especially prominent in ab-stretched CsFe2As2. We also find that the coherent/incoherent electronic behavior of the systems is, apart from temperature, strongly dependent on JH, and we provide estimates of the coherence scale T∗. We discuss these results in the framework of reported experimental observations.

Original languageEnglish
Article number195128
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number19
Publication statusPublished - Nov 16 2015
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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