First-principles study of polar magnets corundum double-oxides Mn2FeMO6 (M = W and Mo)

Abstract

The physical properties of the corundum double-oxides Mn2FeMO6 (M = W and Mo) are investigated using density functional theory (DFT). The structure relaxation in different spin orders are performed and ferrimagnetic is found the most stable magnetic phase. The compounds are dielectric materials with band gap values 1.84 and 2.03 eV. These materials are polar magnets because of the coexistence of contradictory properties such as polarization and magnetization, which are observed very rarely. The electric polarization arises due structure distortion and cation orbital configuration of M atom, while the magnetization occurs due to unpaired dn of Mn and Fe orbital configuration. The compounds understudy are suitable for ferroelectric and magneto-electric applications due to their large spontaneous polarization (58.16 and 69.24 µC/cm2) and magnetic moments (3 and 3.43 µB/f.u). These multiferroic Mn2FeMO6 exhibit a profound interplay between electrical polarization and the applied magnetic field. The calculated values of piezoelectric coefficient, d33 = 264 and 606 pC/N are comparable to lead-based piezoelectric materials. A set of mechanical parameters revealed that Mn2FeMO6 are mechanically stable in rhombohedral phase. The applied strain has great influence on the physical properties of these two compounds.