Mott physics and first-order transition between two metals in the normal-state phase diagram of the two-dimensional Hubbard model

Abstract

For doped two-dimensional Mott insulators in their normal state, the challenge is to understand the evolution from a conventional metal at high doping to a strongly correlated metal near the Mott insulator at zero doping. To this end, we solve the cellular dynamical mean-field equations for the two-dimensional Hubbard model using a plaquette as the reference quantum impurity model and continuous-time quantum Monte Carlo method as impurity solver. The normal-state phase diagram as a function of interaction strength U , temperature T , and filling n shows 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. Associated with this transition, there is a maximum in scattering rate as well as thermodynamic signatures. 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 low temperature transition between two types of metals at finite doping. The influence of Mott physics therefore extends well beyond half-filling.

Intermediate coupling model of the cuprates

“…Recent CDMFT calculations using 2×2 plaquettes have found a similar pseudogap phase diagram, with a transition at low doping between two metallic phases involving a change of FSs [323,324]. In these pure Hubbard model (t = 0) calculations, the small FS-metal at low doping plays the role of the doped (π, π) SDW-metal found in DCA [63], and the large FS-metal corresponds to the nonmagnetic state.…”

“…This interpretation is suggested by a number of factors: (1) Figure 9 of Ref. [324] shows the effective chemical potentials at three k-points vs doping and Hubbard energy U . For (π, 0), corresponding to the VHS, µ ef f crosses [330].…”

“…6 of Ref. [324]], marking the opening of a pseudogap; (2) As noted in Sections 4.3 and 4.5, upon entering a phase of short or long-range order, the self-energy develops a strong momentum dependence, Eqs. 24 and 28.…”

“…9 of Ref. [324]; (3) The large compressibility [325] and strong scattering rate along the Widom line [ Fig. 10 of Ref.…”

Curie-like paramagnetism due to incomplete Zhang-Rice singlet formation in La2−xSrxCuOKaiser1, Huang2, Komiya3 et al. 2012Phys. Rev. B141191View full textAdd to dashboardCite

“…Recently, Sordi et al have shown that doublet formation (total spin S = 1/2) in a one-band Hubbard model grows upon doping the parent Mott insulator. 51 The same is true of the S = 1/2 three-spin polaron present in three-band models, 52,53 where the spin of a hole on the in-plane oxygen is antiparallel to the two nearest-neighbor copper spins. However, the hole in these and the triplet state (total spin S = 1) is mobile, with the effective magnetic moment presumably fluctuating too fast to cause dynamic depolarization of the TF-µSR signal.…”