Electronic structure and improper electric polarization of samarium orthoferrite

The band structure and distributions of the electron and spin densities of samarium orthoferrite have been calculated within the framework of the first-principles density functional theory in the LSDA + $U$ approximation taking into account the collinear antiferromagnetic ordering of the magnetic moments of iron and samarium cations. The possibility of inducing a ferroelectric state at temperatures below the antiferromagnetic ordering temperature of the magnetic sublattice formed by samarium cations has been considered using the results of the group-theoretical analysis. In the high-temperature range, the formation of regions with a spontaneous electric polarization is possible in the presence of additional factors that reduce the symmetry of the crystal.