Optical and Transport Properties

Abstract

AbstractThe iron-based superconductors are in general multiband materials with both electron and hole pockets at the Fermi surface. The presence of multiple carrier types complicates the interpretation of dc transport measurements. However, in the normal state the complex optical properties allow the different contributions to be disentangled, permitting the behavior of the electrons and the holes to be studied using the two-Drude model. The strong, broad Drude term associated with the hole pockets is essentially temperature independent and almost incoherent. Coherent transport originates from the electron pockets where the Drude term is weaker, but the temperature-dependent scattering rate is typically much smaller. The crossover in the optical scattering rates is associated with anomalies observed in transport measurements. Interestingly, the electron pocket can display either a Fermi liquid or a non-Fermi liquid behavior, depending on the nature of the chemical substitution. In the superconducting state the strength of the condensate may be determined as well as the magnitude of the superconducting energy gaps.KeywordsOptical ConductivitySpectral WeightEffective Medium ApproximationHole PocketResidual Resistivity RatioThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.