LDA'+DMFT Investigation of Electronic Structure of K{1-x}Fe{2-y}Se2 Superconductor

TL;DR

This study uses a novel LDA'+DMFT approach to analyze the electronic structure of K{1-x}Fe{2-y}Se2 superconductor, revealing higher correlation effects than in iron pnictides and better agreement with experimental data.

Contribution

First application of LDA'+DMFT to K{1-x}Fe{2-y}Se2, showing improved spectral predictions and insights into band renormalization and symmetry of electronic states.

Findings

Bandwidth renormalization factor about 5

Fe-3d(t2g) bands equally renormalized

Electronic states at Fermi level are predominantly xy symmetry

Abstract

We investigate electronic structure of the new iron chalcogenide high temperature superconductor K{1-x}Fe{2-y}Se2 (hole doped case with x=0.24, y=0.28) in the normal phase using the novel LDA'+DMFT computational approach. We show that this iron chalcogenide is more correlated in a sense of bandwidth renormalization (energy scale compression by factor about 5 in the interval +/-1.5 eV), than typical iron pnictides (compression factor about 2), though the Coulomb interaction strength is almost the same in both families. Our results for spectral densities are in general agreement with recent ARPES data on this system. It is found that all Fe-3d(t2g) bands crossing the Fermi level have equal renormalization, in contrast to some previous interpretations. Electronic states at the Fermi level are of predominantly xy symmetry. Also we show that LDA'+DMFT results are in better agreement with experimental spectral function maps, than the results of conventional LDA+DMFT. Finally we make predictions for photoemission spectra lineshape for K{0.76}Fe{1.72}Se2.