Giant ferroelectric polarization and electric reversal of strong spontaneous magnetization in multiferroic Bi2FeMoO6

BiFeO3 is the most famous multiferroic material, but it has no strong spontaneous magnetization due to its antiferromagnetism. Here we show that giant ferroelectric polarization and strong spontaneous magnetization can be both realized in double perovskite Bi2FeMoO6 with R3 (#146) space group based on BiFeO3. Our first-principles phonon spectra establishes that this multiferroic R3 phase is stable. Our systematic calculations show that it is a spin-polarized semiconductor with gap reaching to 0.54-0.85 eV and has a strong ferroelectric polarization of 85 μC/cm2. This ferroelctricity is comparable with that of BiFeO3, but here obtained is a strong ferrimagnetism. Both ferroelectric polarization and magnetic easy axis are shown to be in pseudocubic [1 1 1] orientation. Our further analysis shows that the macroscopic spontaneous magnetization can be deterministically reversed through a three-step path by external electric field. Therefore, we believe that this Bi2FeMoO6 material can be used to design new multifunctional materials and achieve high-performance devices.