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Advances in Condensed Matter Physics
Volume 2012 (2012), Article ID 398721, 13 pages
http://dx.doi.org/10.1155/2012/398721
Research Article

Charge Order Breaks Magnetic Symmetry in Molecular Quantum Spin Chains

1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany

Received 2 September 2012; Accepted 11 October 2012

Academic Editor: Fabrizio Carbone

Copyright © 2012 M. Dressel et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Charge order affects most of the electronic properties but is believed not to alter the spin arrangement since the magnetic susceptibility remains unchanged. We present electron-spin-resonance experiments on quasi-one-dimensional salts ( PF6, AsF6, and SbF6), which reveal that the magnetic properties are modified below when electronic ferroelectricity sets in. The coupling of anions and organic molecules rotates the g-tensor out of the molecular plane creating magnetically nonequivalent sites on neighboring chains at domain walls. Due to anisotropic Zeeman interaction a novel magnetic interaction mechanism in the charge-ordered state is observed as a doubling of the rotational periodicity of .