Transport criticality at Mott transition in a triangular lattice Hubbard model

Abstract

We study electric transport near the Mott metal-insulator transition in a triangular-lattice Hubbard model at half filling. We calculate optical conductivity $\sigma (\omega )$ based on a cellular dynamical mean field theory including vertex corrections inside the cluster. Near the Mott critical end point, a Drude analysis in the metallic region suggests that the change in the Drude weight is important rather than that in the transport scattering rate for the Mott transition. In the insulating region, there emerges an "ingap" peak in $\sigma (\omega )$ at low $\omega$ near the Mott transition, and this smoothly connects to the Drude peak in the metallic region with decreasing Coulomb repulsion. We find that the weight of these peaks exhibits a power-law behavior upon controlling Coulomb repulsion at the critical temperature. The obtained critical exponent suggests that conductivity does not correspond to magnetization or energy density of the Ising universality class in contrast to several previous works.

14 pages, 17 figures, accepted for publication in Physical Review B

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• Spin-orbit-induced exotic insulators in a three-orbital Hubbard model with $(t_{2g}{)}^5$ electrons
• Magnetic and charge susceptibilities in the half-filled triangular lattice Hubbard model
• Electrical conductivity in the Hubbard model: orbital effects of magnetic field
• Comparative study of the density matrix embedding theory for the Hubbard models
• Doublon Dynamics of the Hubbard Model on Triangular Lattice
• Optical Response in Excitonic Insulating State: Variational Cluster Approach
• Reentrance of metal-insulator transition and magnetic competitions on a triangular lattice with second nearest-neighbor hopping
• Orbital Mott transition in two dimensional Pyrochlore lattice