Perovskite manganites hosting versatile multiferroic phases with symmetric and antisymmetric exchange strictions

Abstract

Complete magnetoelectric (ME) phase diagrams of orthorhombic $R{\text{MnO}}_{3}$ with and without magnetic moments on the $R$ ions have been established. Three kinds of multiferroic ground states, the $ab$-cycloidal, the $bc$-cycloidal, and the collinear $E$-type phases, have been identified by the distinct ME responses. The electric polarization of the $E$-type phase dominated by the symmetric spin exchange $({\mathbit{S}}_{i}\ensuremath{\cdot}{\mathbit{S}}_{j})$ is more than ten times as large as that of the $bc$-cycloidal phase dominated by the antisymmetric one $({\mathbit{S}}_{i}\ifmmode\times\else\texttimes\fi{}{\mathbit{S}}_{j})$ and the ME response is enhanced near the bicritical phase boundary between these multiferroic phases of different origins. These findings may provide generic features of the magnetically induced multiferroics.