다강성 hexagonal RMnO3의 강유전성 발현에 관한 제1원리 연구

Abstract

Multiferroic exhibit simultaneous ferroic properties with coupled electric, magnetic, and structural orders. Recently, these materials have received a great deal of attention due to their potential for Magnetoelectric effect, which is the property that a magnetic field induces an electric polarization and, conversely, an electric field induces a magnetization. Among theses, manganite-based multiferroics have been most extensively studied. Orthorhombic manganites such as TbMnO3 and TbMn2O5 exhibit a strong tendency of the magnetoelectric coupling which stems from a spiral magnetic-ordering-induced improper or pseudo-proper ferroelectricity. In hexagonal manganites (h-RMnO3), on the other hand, a spiral magnetic order is absent and an asymmetric movement of R ions from the centrosymmetric position is known to be a prevailing factor in the manifestation of ferroelectricity.