Eur. Phys. J. B 46, 489-496 (2005)
https://doi.org/10.1140/epjb/e2005-00278-0

Sr₁₄Cu₂₄O₄₁: a complete model for the chain sub-system

¹ Laboratoire de Physique Quantique, IRSAMC - CNRS UMR 5626, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 4, France
² Laboratoire CRISMAT, ENSICAEN - CNRS UMR 6508, 6 boulevard Maréchal Juin, 14050 Caen Cedex, France

Corresponding author: ^a lepetit@ensicaen.fr

Received: 4 March 2005
Revised: 27 June 2005
Published online: 7 September 2005

Abstract

A second neighbor t-J+V model for the chain subsystem of the Sr₁₄Cu₂₄O₄₁ was extracted from ab-initio calculations. This model does not use periodic approximation but describes the entire chain through the use of the four-dimensional crystallographic description. Second neighbors interactions are found to be of same order than the first neighbors ones. The computed values of the second neighbors magnetic interactions are coherent with experimental estimations of the intra-dimer magnetic interactions, even if slightly smaller. The reasons of this underestimation are detailed. The computed model allowed us to understand the origin of the chain dimerisation and predicts correctly the relative occurrence of dimers and free spins. The orbitals respectively supporting the magnetic electrons and the holes have been found to be essentially supported by the copper 3d orbitals (spins) and the surrounding oxygen 2p orbitals (holes), thus giving a strong footing to the existence of Zhang-Rice singlets.