From Hund's insulator to Fermi liquid: Optical spectroscopy study of K doping in BaMn2As2

D. E. McNally, S. Zellman, Z. P. Yin, K. W. Post, Hua He, K. Hao, G. Kotliar, D. Basov, C. C. Homes, M. C. Aronson

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24 Scopus citations


We present optical transmission measurements that reveal a charge gap of 0.86 eV in the local-moment antiferromagnetic insulator BaMn2As2, an order of magnitude larger than previously reported. Density functional theory plus dynamical mean-field theory (DFT+DMFT) calculations correctly reproduce this charge gap only when a strong Hund's coupling is considered. Thus, BaMn2As2 is a member of a wider class of Mn pnictide compounds that are Mott-Hund insulators. We also present optical reflectance for metallic 2%-K-doped BaMn2As2 that we use to extract the optical conductivity at different temperatures. The optical conductivity σ1(ω) exhibits a metallic response that is well described by a simple Drude term. Both σ(ω→0,T) and ρ(T) exhibit Fermi-liquid temperature dependencies. From these measurements, we argue that a more strongly correlated Hund-metal version of the parent compounds of the iron pnictide superconductors has not yet been realized by doping this class of Hund insulators.

Original languageEnglish (US)
Article number115142
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number11
StatePublished - Sep 22 2015

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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