Transport criticality in triangular lattice Hubbard model

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We study electric transport near the Mott metal-insulator transition. Optical conductivity of the half-filled Hubbard model on a triangular lattice is calculated based on a cellular dynamical mean field theory including vertex corrections inside the cluster. By investigating the spectrum at low frequencies, we find that a Drude peak on the metallic side smoothly connects to an "ingap" peak on the insulating side. The optical weight of these peaks exhibits a critical behavior with power-law near the Mott critical end point, |D-D*|∝|U-U*|¹/δ. We find that the critical exponent 1/δ differs from the exponents in the thermodynamics.