First-principles study of the structural, electronic, magnetic, and ferroelectric properties of a charge-ordered iron(ii)-iron(iii) formate framework

Density functional theory calculations have been performed for the structural, electronic, magnetic, and ferroelectric properties of a mixed-valence Fe(ii)-Fe(iii) formate framework [NH₂(CH₃)₂][FeⁱⁱⁱFeⁱⁱ(HCOO)₆]. Recent experiments report a spontaneous electric polarization, and our calculations are in agreement with the reported experimental value. Furthermore, we shed light onto the microscopic mechanism leading to the observed value, as well as on how to possibly enhance the polarization. The interplay between charge ordering, dipolar ordering of DMA⁺ cations, and the induced structural distortions suggest new interesting directions to explore in these complex multifunctional hybrid perovskites.