Theoretical evidence for strong correlations and incoherent metallic state in FeSe

TL;DR

This paper provides theoretical evidence that FeSe exhibits strong electronic correlations, including a lower Hubbard band and non-Fermi liquid behavior, indicating an incoherent metallic state in its normal phase.

Contribution

The study offers the first dynamical mean field theory evidence of strong correlations and incoherent metallicity in FeSe, with specific spectral and orbital-dependent features.

Findings

Presence of a lower Hubbard band in FeSe

Orbital-dependent mass enhancements observed

Normal state identified as a bad metal with non-Fermi liquid behavior

Abstract

The role of electronic Coulomb correlations in iron-based superconductors is an important open question. We provide theoretical evidence for strong correlation effects in the FeSe compound, based on dynamical mean field calculations. A lower Hubbard band is found in the spectral properties. Moreover, together with significant orbital-dependent mass enhancements, we find that the normal state is a bad metal over an extended temperature range, implying a non-Fermi liquid. Predictions for angle-resolved photoemission spectroscopy are made.