From Hunds insulator to Fermi liquid: Optical spectroscopy study of K doping in BaMn${}_2$As${}_2$

Abstract

We present optical transmission measurements that reveal a charge gap of 0.86 eV in the local moment antiferromagnetic insulator BaMn${}_2$As${}_2$, 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, BaMn${}_2$As${}_2$ is a member of a wider class of Mn pnictide compounds that are Mott-Hund's insulators. We also present optical reflectance for metallic 2% K doped BaMn${}_2$As${}_2$ that we use to extract the optical conductivity at different temperatures. The optical conductivity ${\sigma }_1$($\omega$) exhibits a metallic response that is well described by a simple Drude term. Both $\sigma$($\omega$$\to$0, T) and $\rho$(T) exhibit Fermi liquid temperature dependencies. From these measurements, we argue that a more strongly correlated Hund's metal version of the parent compounds of the iron pnictide superconductors has not yet been realized by doping this class of Hund's insulators.

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Cited by in corpus (23)

• Magnetic hexadecapole order and magnetopiezoelectric metal in Ba${}_{1-x}$K${}_x$Mn${}_2$As${}_2$
• Nematicity at the Hund's metal crossover in iron superconductors
• Hund's induced Fermi-liquid instabilities and enhanced quasiparticle interactions
• Modeling many-body physics with Slave-Spin Mean-Field: Mott and Hund's physics in Fe-superconductors
• Metallic behavior induced by potassium doping of the trigonal antiferromagnetic insulator EuMn2As2
• ARPES observation of Mn-pnictide hybridization and negligible band structure renormalization in BaMn${}_2$As${}_2$ and BaMn${}_2$Sb${}_2$
• Spin-orbital-momentum locking under odd-parity magnetic quadrupole ordering
• Synergy between Hund-driven correlations and boson-mediated Superconductivity
• Antiferromagnetic Skyrmions and Skyrmion Density Wave in Rashba Hund's Insulator
• Importance of effective dimensionality in manganese pnictides
• \textit{Ab initio} study on spin fluctuations of itinerant kagome magnet FeSn
• Itinerant antiferromagnetic BaMn${}_2$Pn${}_2$'s showing both negative and positive magnetoresistances
• Robust antiferromagnetic spin waves across the metal-insulator transition in hole-doped BaMn${}_2$As${}_2$
• On the nature of the Mott transition in multiorbital systems
• Correlations and incipient antiferromagnetic order within the linear Mn chains of metallic Ti${}_4$MnBi${}_2$
• Charge disproportionation and Hund's insulating behavior in a five-orbital Hubbard model applicable to $d^4$ perovskites
• Slave-spin mean field for broken-symmetry states: Néel antiferromagnetism and its phase separation in multi-orbital Hubbard models
• Incoherent electronic band states in Mn-substituted BaFe${}_2$As${}_2$
• Thermopower of the electron-doped manganese pnictide LaMnAsO
• Nematic spectral signatures of the Hund's metal
• Spin dynamics in itinerant antiferromagnet SrCr${}_2$As${}_2$
• Local-moment magnetism in Mn-based pnictides
• PhD Thesis: Electronic correlations in multiorbital systems