Formation of As-As Bond and Its Effect on Absence of Superconductivity in Collapsed Tetragonal Phase of Ca0.86Pr0.14Fe2As2 : An Optical Spectroscopy Study

TL;DR

This study investigates how As-As bond formation in Ca0.86Pr0.14Fe2As2's collapsed tetragonal phase suppresses superconductivity by altering electronic structure and hybridization, revealed through optical spectroscopy and band structure analysis.

Contribution

It provides new insights into the role of As-As bonds in the absence of superconductivity in the cT phase of Ca0.86Pr0.14Fe2As2, combining experimental and theoretical approaches.

Findings

Formation of a midinfrared peak near 0.4 eV in optical conductivity.

Reduced electron correlation after the cT phase transition.

Transition to a nonmagnetic Fermi liquid system without superconductivity.

Abstract

The temperature dependence of in plane optical conductivity has been investigated for Ca0.86Pr0.14Fe2As2 which shows a structural transition from tetragonal (T) to collapsed tetragonal(cT) phase at TcT=73 K. Upon entering the cT phase, drastic change characterized by the formation of a midinfrared peak near 3200 cm-1(0.4 eV) in the optical conductivity is observed.Analysis of the spectral weight reveals reduced electron correlation after the cT phase transition.Based on the calculated band structure and simulated optical conductivity, we attribute the new feature around 0.4 eV to the formation of interlayer As-As bond. The As-As bond strongly affects the Fe-As hybridizations, and in turn, drastically changes the Ca0.86Pr0.14Fe2As2 into a nonmagnetic Fermi liquid system without bulk superconductivity in the cT phase.