From Hubbard bands to spin-polaron excitations in the doped Mott materialNaxCoO2

2014/08/09 by Aljoscha Wilhelm, Frank Lechermann, Hartmut Hafermann +4 · 10 citations
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Condensed matter physics #Doping #Excitation #Ferromagnetism #Hubbard model #Magnetic and transport properties of perovskites and related materials #Mott insulator #Physics #Physics of Superconductivity and Magnetism #Polaron #Quantum mechanics #Quasiparticle #Spin (aerodynamics) #Superconductivity #cond-mat.str-el

paper · pdf · doi:10.1103/physrevb.91.155114

published in Physical Review B 91(15) (American Physical Society) · 5 pages, 3 figures; supplementary material

arxiv created 2014/08/09 · openalex publication_date 2015/04/10 · arxiv updated 2015/04/16 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05

Abstract

We investigate the excitation spectrum of strongly correlated sodium cobaltate within a realistic many-body description beyond dynamical mean-field theory (DMFT). At lower doping around x=0.3, rather close to Mott-critical half-filling, the single-particle spectral function of Na_xCoO₂ displays an upper Hubbard band which is captured within DMFT. Momentum-dependent self-energy effects beyond DMFT become dominant at higher doping. Around a doping level of x\ensuremath∼0.67, the incoherent excitations give way to finite-energy spin-polaron excitations in close agreement with optics experiments. These excitations are a direct consequence of the formation of bound states between quasiparticles and paramagnons in the proximity of in-plane ferromagnetic ordering.

Citations

• Polarization dependence of x-ray absorption spectra ofNaxCoO2: Electronic structure from cluster calculations
• Infrared Probe of the Electronic Structure and Charge Dynamics ofNa0.7CoO2
• Ferromagnetic In-Plane Spin Fluctuations inNaxCoO2Observed by Neutron Inelastic Scattering
• Correlation Effects on the Doped Triangular Lattice in View of the Physics of Sodium-RichNaxCoO2
• Charge transport of electron-doped Mott insulators on a triangular lattice
• Spin correlations and cobalt charge states: Phase diagram of sodium cobaltates
• Strong Correlations Produce the Curie-Weiss Phase ofNaxCoO2
• Charge Ordering, Commensurability, and Metallicity in the Phase Diagram of the LayeredNaxCoO2
• Continuous-time Monte Carlo methods for quantum impurity models

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