Magnetically-driven ferroelectric atomic displacements of the order of 10−3Angstromhavebeenobservedinorthorhombic(perovskitelike)YMnO_3byasingle−crystalsynchrotronx−raydiffraction.TherefinedpolarstructureshowsthecharacteristicbondalternationdrivenbytheexchangestrictioninstaggeredMn−O−Mnarrayswith\uparrow\uparrow\downarrow\downarrow$ type ordering, giving rise to a spontaneous polarization along a-axis. First-principles calculations based on the Berry phase method as well as on the experimentally refined crystal structure can reproduce the observed polarization value.
@article{arxiv.1107.2467,
title = {Magnetically-Driven Ferroelectric Atomic Displacements in perovskite like YMnO3},
author = {D. Okuyama and S. Ishiwata and Y. Takahashi and K. Yamauchi and S. Picozzi and K. Sugimoto and H. Sakai and M. Takata and R. Shimano and Y. Taguchi and T. Arima and Y. Tokura},
journal= {arXiv preprint arXiv:1107.2467},
year = {2011}
}