Pressure Suppression of Electron Correlation in the Collapsed Tetragonal Phase of $CaF{e}_{2}A{s}_2$ : A DFT-DMFT Investigation

Abstract

Recent studies reveal a pressure induced transition from a paramagnetic tetragonal phase (T) to a collapsed tetragonal phase (CT) in $CaF{e}_{2}A{s}_2$, which was found to be superconducting with non-hydrostatic pressure at low temperature. We have investigated the effects of electron correlation and local fluctuating moment in both tetragonal and collapsed tetragonal phases of the paramagnetic $CaF{e}_{2}A{s}_2$ using self consistent DFT+DMFT with continuous time quantum Monte Carlo as the impurity solver. From the computed optical conductivity, we find a gain in the optical kinetic energy due to the loss in Hund's rule coupling energy in the CT. We find that the transition from T to CT turns $CaF{e}_{2}A{s}_2$ from a bad metal into a good metal. Computed mass enhancement and local moments also show significant decrease in the CT, which confirms the suppression of the electron correlation in the CT phase of $CaF{e}_{2}A{s}_2$.

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• Role of electron-electron interactions in the charge dynamics of rare-earth-doped CaFe2As2
• Drastic electronic structure reconstruction of Ca${}_{1-x}$Pr${}_x$Fe${}_2$As${}_2$ in the collapsed tetragonal phase
• Optical spectroscopy study of the collapsed tetragonal phase of CaFe${}_2$(As${}_{0.935}$P${}_{0.065}$)${}_2$ single crystals
• Electronic Correlations and Absence of Superconductivity in the Collapsed Phase of LaFe${}_2$As${}_2$