The Two Flavours of Iron-Pnitctides: Optical Investigations on the 122 Family
Prof. Dr. Martin Dressel (Universitat Stuttgart)

Optical experiments are a very powerful tool to explore the electrodynamic properties of iron-pnictides. We gain information on the metallic state where two electronic subsystems can be identified, one revealing a hidden Fermi-liquid behavior. There are indications of intermediate correlation effects since the spectral weight does not recover. EuFe₂As₂ undergoes a SDW transition at 189 K and a partial gap opens in the density of states. Upon passing through the transition the phonons are modified by electron-phonon coupling. Electron doped BaFe₂As₂ are superconductors around 25 K. In the optical conductivity clear evidence if found of an isotropic gap which eventually opening over the entire Fermi surface.