Pseudogap temperature as a Widom line in doped Mott insulators

TL;DR

This paper demonstrates that the pseudogap temperature in doped Mott insulators corresponds to a Widom line associated with a crossover above a first-order transition, explaining the pseudogap without invoking broken symmetry.

Contribution

It identifies the pseudogap temperature as a Widom line in the Hubbard model, linking it to thermodynamic anomalies and a crossover rather than symmetry breaking.

Findings

Pseudogap temperature T* is a crossover line above a first-order transition.

The Widom line organizes the pseudogap phase diagram.

Broken symmetry states are not necessary to explain the pseudogap.

Abstract

The pseudogap refers to an enigmatic state of matter with unusual physical properties found below a characteristic temperature $T^*$ in hole-doped high-temperature superconductors. Determining $T^*$ is critical for understanding this state. Here we study the simplest model of correlated electron systems, the Hubbard model, with cluster dynamical mean-field theory to find out whether the pseudogap can occur solely because of strong coupling physics and short nonlocal correlations. We find that the pseudogap characteristic temperature $T^*$ is a sharp crossover between different dynamical regimes along a line of thermodynamic anomalies that appears above a first-order phase transition, the Widom line. The Widom line emanating from the critical endpoint of a first-order transition is thus the organizing principle for the pseudogap phase diagram of the cuprates. No additional broken symmetry is necessary to explain the phenomenon. Broken symmetry states appear in the pseudogap and not the other way around.