Volume 79, Number 2, July 2007
Article Number 27003
Number of page(s) 5
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
Published online 03 July 2007
EPL, 79 (2007) 27003
DOI: 10.1209/0295-5075/79/27003

Magnetic order of the CuO2 chains in (Sr,Ca)14Cu24O41

U. Schwingenschlögl and C. Schuster

Institut für Physik, Universität Augsburg - 86135 Augsburg, Germany

received 29 March 2007; accepted in final form 5 June 2007; published July 2007
published online 3 July 2007

We investigate the magnetism of the CuO2 chains in the spin-chain compounds (Ca,Sr)14Cu24O41 by means of LDA+U electronic structure calculations. The study is based on an effective model of two coupled CuO2 chains, which captures the structural prerequisites of the exchange interaction. We determine the total energy of various spin configurations on coupled CuO2 chains. In particular, we find that the ground state of Ca-rich spin-chain compounds is given by an antiferromagnetic intrachain spin order with $4k_{{\rm F}}$-periodic charge order, complemented by likewise antiferromagnetic interchain ordering.

71.10.Pm - Fermions in reduced dimensions (anyons, composite fermions, Luttinger liquid, etc.).
75.25.+z - Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source X-ray scattering, etc.).
75.30.Et - Exchange and superexchange interactions.

© Europhysics Letters Association 2007