We present a study of the tetragonal to collapsed-tetragonal transition of ${\mathrm{CaFe}}_2{\mathrm{As}}_2$ using angle-resolved photoemission spectroscopy 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.

• Received 14 May 2015
• Revised 28 May 2016

DOI:https://doi.org/10.1103/PhysRevB.93.245139