Pseudogap and the specific heat of high $T_c$ superconductors

TL;DR

This study investigates how the pseudogap affects the specific heat in a 2D Hubbard model, revealing a two-peak structure and the influence of occupation and hopping parameters on these phenomena.

Contribution

It introduces a self-consistent two-pole approximation to analyze the pseudogap's impact on specific heat, highlighting the role of correlations and hopping in high-Tc superconductors.

Findings

Specific heat decreases above occupation n_T≈0.85 due to pseudogap formation.

A robust two-peak structure in specific heat is observed, affected by occupation but not Coulomb interaction U.

Second nearest neighbor hopping significantly influences the pseudogap and specific heat behavior.

Abstract

The specific heat of a two dimensional repulsive Hubbard model with local interaction is investigated. We use the two-pole approximation which exhibits explicitly important correlations that are sources of the pseudogap anomaly. The interplay between the specific heat and the pseudogap is the main focus of the present work. Our self consistent numerical results show that above the occupation $n_T\approx 0.85$, the specific heat starts to decrease due to the presence of a pseudogap in the density of states. We have also observed a two peak structure in the specific heat. Such structure is robust with respect to the Coulomb interaction $U$ but it is significantly affected by the occupation $n_T$. A detailed study of the two peak structure is carried out in terms of the renormalized quasi-particle bands. The role of the second nearest neighbor hopping on the specific heat behavior and on the pseudogap, is extensively discussed.