1. Condensed-Matter Physics & Materials Science Seminar

    "Incoherent Charge Dynamics and Role of Electronic Correlations in Iron Pnictides"

    Presented by Shin-ichi Uchida, University of Tokyo, Japan

    Thursday, November 7, 2013, 1:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: John P. Hill

    We have carried out a comparative study of the in-plane resistivity and the optical conductivity spectrum of BaFe2As2 and other transition-metal pnictides with the same crystal structure, including BaCo2As2, BaFe2P2, and KFe2As2, which are linked with BaFe2As2 via chemical substitution (doping). It is found that, in the high-temperature phase, charge dynamics is highly incoherent with coherent Drude component occupying an only small fraction of the low-energy spectral weight for the two iron arsenides, BaFe2As2 and KFe2As2 , whereas it is highly coherent for the other pnictides. The fraction of the coherent Drude spectral weight in the low-energy spectrum, the degree of coherence, is found to be well correlated with the transition metal (TM)-pnictogen bond angle and the electron filling of TM-3d orbitals indicating that electronic correlations are strong in iron arsenides and that doping controls the correlation strength in different ways depending on the type of doping and the dopant site. [1] M. Nakajima, S. Ishida, H. Eisaki, S. Uchida et al., "Normal-state char ge dynamics in doped BaFe2As2: Roles of doping and necessary ingredients for superconductivity", arXiv: 1308.6133. [2] M. Nakajima, S. Ishida, H. Eisaki, S. Uchida et al., " Strong electronic correlations in iron pnictides: Comparison of the3 optical spectra for BaFe2As2-related compounds", arXiv: 1308.6113.