We propose a mechanism for the observed stacking charge order in the quarter-filled ladder compound NaV2O5. Via a standard mapping of the charge degrees of freedom onto Ising spins we explain the stacking order as a result of competition between couplings of the nearest and next-nearest planes with the 4-fold degenerate super-antiferroelectric in-plane order.
@article{arxiv.cond-mat/0407700,
title = {On the Stacking Charge Order in NaV2O5},
author = {G. Y. Chitov and C. Gros},
journal= {arXiv preprint arXiv:cond-mat/0407700},
year = {2009}
}