The optical conductivity of (K,Rb,Cs)Fe₂As₂: hidden temperature behaviors and electronic correlations strength

We measured the temperature dependence of the optical reflectivity in undoped XFe2As2 iron pnictides, where X = K, Rb, and Cs. A two-Drude analysis of the data quantitatively describes the Kramers-Kronig obtained optical conductiity of all compositions. From this analysis, we extracted the scattering rate and effective mass for each Drude contribution. Both our parameters and the overall optical conductivity are compared to first principles DMFT calculations. We discuss the tempeature behavior of the scattering rate as a funciton of X and show that a hidden linear behavior emerges from the decomposition of the optical conductivity. The comparison of the full optical conductivity to DMFT caculations allows us to infer the evolution of the electronic correlations strength with ionic replacement.
Collaborators: L. de' Medici, (ESPCI Paris, France), F. Hardy, A.A. Haghighirad (Karlsruhe Institute of Technology, Germany)