High-Curie-temperature ferrimagnetism and ferroelectricity in Bi2FeMoO6

TL;DR

This study predicts that Bi2FeMoO6, a double perovskite, exhibits high-temperature ferrimagnetism and ferroelectricity, making it a promising multiferroic material for advanced multifunctional devices.

Contribution

First-principles calculations reveal Bi2FeMoO6 as a stable, high-temperature multiferroic with strong ferrimagnetism and ferroelectricity, expanding the family of room-temperature multiferroic materials.

Findings

Semiconductor with 0.725 eV gap

Ferrimagnetism with 650 K Curie temperature

Ferroelectric polarization of 85 μC/cm²

Abstract

BiFeO3 is the most famous multiferroic material, but its G-type antiferromagnetism is highly desirable to be replaced by strong macroscopic magnetism beyond room temperature. Here we obtain double perovskite Bi2FeMoO6 with R3 (#146) space group by substituting Mo for 50% Fe in BiFeO3. Our first-principles calculated results show that it is a semiconductor with gap reaching to 0.725 eV, its net magnetic moment is 2\mu_B per formula unit, and its ferroelectric polarization is 85\mu C/cm^2. This ferroelctricity is comparable with that of BiFeO3, but here the magnetism is a strong ferrimagnetism with Curie temperature of 650 K. Our first-principles phonon spectra establishes that this R3 phase is stable. Electric polarization and magnetic easy axis are shown to be in pseudo-cubic [111] axis. Our further analysis shows that the multiferroic mechanism is similar to that in BiFeO3. Therefore, this Bi2FeMoO6 can be used to achieve strong macroscopic magnetism and ferroelectricity well above room temperature, being useful for designing new multifunctional materials and devices.