Tetragonal and collapsed-tetragonal phases of CaFe2As2 -- a view from angle-resolved photoemission and dynamical mean field theory

TL;DR

This study investigates the electronic structure changes in CaFe2As2 during the transition from tetragonal to collapsed-tetragonal phases using advanced experimental and theoretical methods, revealing reduced correlations and the importance of momentum-dependent corrections.

Contribution

The paper combines angle-resolved photoemission experiments with a novel theoretical approach to accurately describe low-energy quasiparticle dispersions in CaFe2As2.

Findings

Collapsed-tetragonal phase shows reduced electronic correlations.

Stronger Fe-As hybridization increases coherence temperature.

Momentum-dependent corrections are crucial for accurate spectral descriptions.

Abstract

We present a study of the tetragonal to collapsed-tetragonal transition of CaFe2As2 using angle-resolved photoemission experiments and dynamical mean field theory-based electronic structure calculations. We observe that the collapsed-tetragonal phase exhibits reduced correlations and a higher coherence temperature due to the stronger Fe-As hybridization. Furthermore, a comparison of measured photoemission spectra and theoretical spectral functions shows that momentum-dependent corrections to the density functional band structure are essential for the description of low-energy quasiparticle dispersions. We introduce those using the recently proposed combined "Screened Exchange + Dynamical Mean Field Theory" scheme.