Eur. Phys. J. B 55, 43-47 (2007)
https://doi.org/10.1140/epjb/e2007-00040-8

Electronic structure of spin-chain compounds: common features

Institut für Physik, Universität Augsburg, 86135 Augsburg, Germany

Corresponding author: ^a Udo.Schwingenschloegl@physik.uni-augsburg.de

Received: 24 August 2006
Revised: 22 November 2006
Published online: 9 February 2007

Abstract

The incommensurate composite systems M₁₄Cu₂₄O₄₁ (M = Ca, Sr, La) are based on two fundamental structural units: CuO₂ chains and Cu₂O₃ ladders. We present electronic structure calculations within density functional theory in order to address the interrelations between chains and ladders. The calculations account for the details of the crystal structure by means of a unit cell comprising 10 chain and 7 ladder units. It turns out that chains and ladders can be treated independently, which allows us to introduce a model system based on a reduced unit cell. For the CuO₂ chains, we find two characteristic bands at the Fermi energy. Tight binding fits yield nearest and next-nearest neighbour interactions of the same order of magnitude.