Ab initio prediction of a multiferroic with large polarization and magnetization

We describe the design of a 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 ferrimagnetic behavior. We show that the ordered perovskite Bi2FeCrO6 will have a polarization of ∼80μC∕cm2, a piezoelectric coefficient of 283μC∕cm2, and a magnetization of ∼160emu∕cm3 (2μB per formula unit), far exceeding the properties of any known multiferroic.