Recent results in the context of model for ladders.

ELBIO DAGOTTO, GEORGE MARTINS, CLAUDIO GAZZA AND ANDRÉ MALVEZZI

STRIPES AND RELATED PHENOMENA (Selected Topics in Superconductivity)

Kluwer Academic Publishers Group

Lugar: New York; Año: 1998; p. 437 - 445

Recent calculations in the context of ladder systems, but with implications also for high-Tc two-dimensional (2D) systems, are described here. In particular, efforts are concentrated on the influence of a hole-hole electrostatic repulsion on holepair binding in the t−J model on ladders. It is concluded that the pairs are very robust because a nearest-neighbor hole-hole repulsion of strength ~5J is needed to break the pairs. In the second part of the paper, the spectral function of holes is provided on up to 2×20 clusters using a new numerical technique. A gap in the spectrum caused by hole binding is observed, as well as flat regions near (π, 0). Implications for studies of high-Tc materials are discussed.