Mott transition, Widom line and pseudogap in the half-filled triangular lattice Hubbard model

Abstract

The Mott transition is observed experimentally in materials that are magnetically frustrated so that long-range order does not hide the Mott transition at finite temperature. Using the dynamical cluster approximation for the half-filled Hubbard model on the triangular lattice, we show that a) the Widom line that extends above the critical point of the first-order Mott transition exists in the thermodynamic limit; b) the presence of this line argues for the existence of the Mott transition in the thermodynamic limit; c) the loss of spectral weight in the metal to Mott insulator transition for strong interactions is momentum dependent, the hallmark of a pseudogap; d) the pseudogap to Mott insulator crossover line is a Frenkel line, analogous to the recently discovered crossover discussed in the statistical physics of the liquid-gas transition. Since the Mott transition and the liquid-gas transition are both in the Ising universality class, the Widom and Frenkel lines can be considered as very general emergent phenomena that arise in both ordinary liquids and electron liquids.