We describe the design of a new magnetic ferroelectric with large spontaneous magnetization and polarization using first-principles density functional theory. The usual difficulties associated with the production of robustly-insulating ferromagnets are circumvented by incorporating the magnetism through {\it ferri-}magnetic behavior. We show that the the ordered perovskite \BFCO will have a polarization of ∼80 μC/cm2, a piezoelectric coefficient of 283 μC/cm2, and a magnetization of ∼160 emu/cm3 (2 μB per formula unit), far exceeding the properties of any known multiferroic.
@article{arxiv.cond-mat/0410268,
title = {Ab-initio prediction of a new multiferroic with large polarization and magnetization},
author = {Pio Baettig and Nicola Spaldin},
journal= {arXiv preprint arXiv:cond-mat/0410268},
year = {2011}
}