Finite doping signatures of the Mott transition in the two-dimensional Hubbard model

The evolution from the conventional metal at high doping to the Mott insulator at zero doping remains a central problem in physics of copper-oxide superconductors. Here we solve the cellular dynamical mean-field equations [1,2] for the two-dimensional Hubbard model on a plaquette with continuous-time quantum Monte Carlo [3,4]. The normal-state phase diagram as a function of temperature T, interaction strength U, and filling n reveals that, upon increasing n towards the Mott insulator, there is a surface of first-order transition between two metals at nonzero doping. That surface ends at a finite temperature critical line originating at the half-filled Mott critical point [5,6]. There is a maximum in scattering rate associated with this transition. These findings suggest a new scenario for the normal-state phase diagram of the high temperature superconductors. The criticality surmised in these systems can originate not from a T=0 quantum critical point, nor from the proximity of a long-range ordered phase, but from a very low temperature transition between two types of normal state metals at finite doping. The influence of Mott physics extends well beyond half-filling. \\[4pt] [1] G. Kotliar et al., Rev. Mod. Phys. 78, 865 (2006).\\[0pt] [2] T. Maier et al., Rev. Mod. Phys. 77, 1027 (2005).\\[0pt] [3] P. Werner and A.J. Millis, Phys. Rev. B 74, 155107 (2006).\\[0pt] [4] K. Haule, Phys. Rev. B 75, 155113 (2007).\\[0pt] [5] G. Sordi, K. Haule, and A.-M.S. Tremblay, Phys. Rev. Lett. 104, 226402 (2010).\\[0pt] [6] G. Sordi, K. Haule, and A.-M.S. Tremblay, unpublished (2010).