# Specific heat maximum as a signature of Mott physics in the two-dimensional Hubbard model

## TL;DR

This paper shows that the peak in specific heat in the doped Mott insulator regime of the 2D Hubbard model signals a finite-temperature critical endpoint of a first-order transition, linking thermodynamic anomalies to Mott physics.

## Contribution

The study identifies the specific heat maximum as a signature of a critical endpoint in the Hubbard model, providing a thermodynamic perspective on Mott physics without requiring broken symmetries.

## Key findings

- Specific heat diverges at the critical endpoint of a first-order transition.
- The anomalies occur at half-filling as a function of interaction strength.
- The results are relevant for organic superconductors and ultracold atoms.

## Abstract

Recent experiments on cuprates show that as a function of doping, the normal-state specific heat sharply peaks at the doping $\delta^*$, where the pseudogap ends at low temperature. This finding is taken as the thermodynamic signature of a quantum critical point, whose nature has not yet been identified. Here we present calculations for the two-dimensional Hubbard model in the doped Mott insulator regime, which indicate that the specific heat anomaly can arise from the finite temperature critical endpoint of a first-order transition between a pseudogap phase with dominant singlet correlations and a metal. As a function of doping at the temperature of the endpoint, the specific heat diverges. Upon increasing temperature, the peak becomes broader. The diverging correlation length is associated with uniform density fluctuations. No broken symmetries are needed. These anomalies also occur at half-filling as a function of interaction strength, and are relevant for organic superconductors and ultracold atoms.