A combination of density functional theory calculations, many-body model considerations, magnetization and electron spin resonance measurements shows that the multiferroic FeTe2O5Br should be described as a system of alternating antiferromagnetic S=5/2 chains with strong Fe-O-Te-O-Fe bridges weakly coupled by two-dimensional frustrated interactions, rather than the previously reported tetramer models. The peculiar temperature dependence of the incommensurate magnetic vector can be explained in terms of interchain exchange striction being responsible for the emergent net electric polarization.
@article{arxiv.1202.4799,
title = {Multiferroic FeTe$_2$O$_5$Br: Alternating spin chains with frustrated interchain interactions},
author = {M. Pregelj and H. O. Jeschke and H. Feldner and R. Valentí and A. Honecker and T. Saha-Dasgupta and H. Das and S. Yoshii and T. Morioka and H. Nojiri and H. Berger and A. Zorko and O. Zaharko and D. Arčon},
journal= {arXiv preprint arXiv:1202.4799},
year = {2012}
}