Pressure Suppression of Electron Correlation in the Collapsed Tetragonal Phase of $CaFe_2As_2$ : A DFT-DMFT Investigation

Subhasish Mandal; R. E. Cohen; K. Haule

doi:10.1103/physrevb.90.060501

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arXiv · 1407.4876

Pressure Suppression of Electron Correlation in the Collapsed Tetragonal Phase of $CaFe_2As_2$ : A DFT-DMFT Investigation

Subhasish Mandal·R. E. Cohen·K. Haule

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Abstract

Recent studies reveal a pressure induced transition from a paramagnetic tetragonal phase (T) to a collapsed tetragonal phase (CT) in $CaFe_2As_2$, 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 $CaFe_2As_2$ 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 $CaFe_2As_2$ 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 $CaFe_2As_2$.

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Subhasish Mandal, R. E. Cohen, K. Haule. 2014-07-18. Pressure Suppression of Electron Correlation in the Collapsed Tetragonal Phase of $CaFe_2As_2$ : A DFT-DMFT Investigation. https://doi.org/10.1103/physrevb.90.060501

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