Many-body effects in high-Tc materials: anomalous properties in the pseudogap region

• Published in: Superconductor science & technology 2012-02, Vol.25 (2), p.025011
• Main Authors: Calegari, E J, Lobo, C O, Magalhães, S G, Chaves, C M, Troper, A
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electronic structure; Exact sciences and technology; Physics; Properties of type I and type II superconductors; Superconductivity
• ISSN: 0953-2048; 1361-6668
• DOI: 10.1088/0953-2048/25/2/025011

Anomalous properties of the normal state of a strongly correlated electron system described by an attractive extended Hubbard model are investigated. The equations of motion of the Green's functions are calculated with the two-pole approximation which gives rise to quasiparticle renormalized bands. The two-pole approximation leads to a set of correlation functions. In particular, the antiferromagnetic correlation function plays an important role as a source of anomalies in the normal state of the model. The uniform static magnetic susceptibility as a function of occupation nT and temperature is calculated. At low temperatures, the susceptibility presents a peak for nT 0.80. The results suggest that it is the onset of short-range antiferromagnetic correlations, which could be a mechanism for the pseudogap. The Fermi surface, defined by the spectral function , is presented for different dopings. It has been observed that above nT 0.80 the ordinary Fermi surface evolves to a hole pocket with pseudogaps near the antinodal points (0,π) and (π,0).