Interplay between condensation energy, pseudogap and the specific heat of a Hubbard model in a n-pole approximation

TL;DR

This paper investigates the relationship between condensation energy, pseudogap, and specific heat in a two-dimensional Hubbard model using a Green's function approach with an n-pole approximation, relevant to high-Tc superconductors.

Contribution

It introduces a Green's function method within an n-pole approximation to study superconductivity and pseudogap phenomena in the Hubbard model with d-wave pairing.

Findings

Pseudogap regime emerges with strong antiferromagnetic correlations.

Specific heat jump and condensation energy decrease above a certain occupation.

The model captures key features of high-Tc superconductor behavior.

Abstract

The condensation energy and the specific heat jump of a two-dimensional Hubbard model, suitable to discuss high-$T_c$ superconductors, is studied. In this work, the Hubbard model is investigated by the Green's function method within a $n$-pole approximation, which allows to consider superconductivity with $d_{x^2-y^2}$-wave pairing. In the present scenario, the pseudogap regime emerges when the antiferromagnetic (AF) correlations become sufficiently strong to move to lower energies the region around of the nodal point $(\pi,\pi)$ on the renormalized bands. It is observed that above a given total occupation $n_T$, the specific heat jump $\Delta C$ and also the condensation energy $U(0)$ decrease signaling the presence of the pseudogap.