Gap anisotropy of layered cuprates in the framework of a correlated hopping model

✍ Scribed by Alexander A. Donkov; Todor M. Mishonov

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 142 KB
• Volume: 21
• Category: Article
• ISSN: 0749-6036
• DOI: 10.1006/spmi.1996.0418

✦ Synopsis

The superconductivity of the conducting CuO 2 plane of the layered cuprates is considered in the framework of a two-dimensional (2D) tight-binding model which contains O2 p σ and Cu3d x 2 -y 2 states. Besides the standard LCAO amplitudes the correlated hopping between O2 p σ and Cu3d x 2 -y 2 orbitals is also considered. The fact that the conduction band is mainly oxygen like and that the one electron hopping between next nearest neighbours (NNN) oxygen ions is relatively smaller then the nearest neighbours (NN) hopping between NN Cu and O ions is taken into account. The equations for the superconducting gap are derived. It is shown that such a choice of the orbitals leads to a s-type superconducting gap, which is in qualitative agreement with data for strongly irradiated samples. It is briefly discussed that the addition to the Emery model of the Cu4s orbital could lead to a d-type gap in agreement with the π-shift of the Josephson effect and location of (p) zeroes by recent ARPES data.