paper

Universal Decomposition of the Low-Frequency Conductivity Spectra of Iron-Pnictides Uncovering Fermi-Liquid Behavior

arXiv:0912.3334 · doi:10.1103/PhysRevB.81.100512

Abstract

Infrared reflectivity measurements on 122 iron-pnictides reveal the existence of two electronic subsystems. The one gapped due to the spin-density-wave transition in the parent materials, such as EuFe $_{2}$ As $_{2}$ , is responsible for superconductivity in the doped compounds, like Ba(Fe $_{0.92}$ Co $_{0.08})_{2}$ As $_{2}$ and Ba(Fe $_{0.95}$ Ni $_{0.05})_{2}$ As $_{2}$ . Analyzing the dc resistivity and scattering rate of this contribution, a hidden $T^{2}$ dependence is found, indicating that superconductivity evolves out of a Fermi-liquid state. The second subsystem gives rise to incoherent background, present in all 122 compounds, which is basically temperature independent, but affected by the superconducting transition.

5 pages, 4 figures