Mottness on a triangular lattice

Abstract

We study the physics on the paramagnetic side of the phase diagram of the cobaltates, $N{a}_{x}Co{O}_2$, with an implementation of cellular dynamical mean field theory (CDMFT) with the non-crossing approximation (NCA) for the one-band Hubbard model on a triangular lattice. At low doping we find that the low energy physics is dominated by a quasi-dispersionless band. At half-filling, we find a metal-insulator transition at $U_c=5.6\pm 0.15t$ which depends weakly on the cluster size. The onset of the metallic state occurs through the growth of a coherence peak at the chemical potential. Away from half filling, in the electron-doped regime, the system is metallic with a large, continuous Fermi surface as seen experimentally. Upon hole doping, a quasi non-dispersing band emerges at the top of the lower Hubbard band and controls the low-energy physics. This band is a clear signature of non-Fermi liquid behavior and cannot be captured by any weakly coupled approach. This quasi non-dispersive band, which persists in a certain range of dopings, has been observed experimentally. We also investigate the pseudogap phenomenon in the context of a triangular lattice and we propose a new framework for discussing the pseudogap phenomena in general. This framework involves a momentum-dependent characterization of the low-energy physics and links the appearance of the pseudogap to a reconstruction of the Fermi surface without invoking any long range order or symmetry breaking. Within this framework we predict the existence of a pseudogap for the two dimensional Hubbard model on a triangular lattice in the weakly hole-doped regime.

14 pages, 21 figures

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Cited by in corpus (16)

• Kondo Metal and Ferrimagnetic Insulator on the Triangular Kagomé Lattice
• Ground state phase diagram of the triangular lattice Hubbard model by density matrix renormalization group method
• Doped Mott Insulators in the Triangular Lattice Hubbard Model
• Mott transition in two-dimensional frustrated compounds
• Mott transition in the Hubbard model on the anisotropic kagomé lattice
• Mott transition in the triangular lattice Hubbard model: a dynamical cluster approximation study
• Magnetic and charge susceptibilities in the half-filled triangular lattice Hubbard model
• Transport criticality at Mott transition in a triangular lattice Hubbard model
• Considerable non-local electronic correlations in strongly doped Na${}_x$CoO${}_2$
• Magnetic phases of the anisotropic triangular lattice Hubbard model
• Comparative study of the density matrix embedding theory for the Hubbard models
• Theory of carrier concentration-dependent electronic behavior in layered cobaltates
• Not all doped Mott insulators have a pseudogap: key role of van Hove singularities
• Transport and spectroscopic signatures of a disorder-stabilized metal in two-dimensional frustrated Mott insulators
• Reentrance of metal-insulator transition and magnetic competitions on a triangular lattice with second nearest-neighbor hopping
• Site-resolved observables in the doped spin-imbalanced triangular Hubbard model