Room-temperature electric polarization induced by phase separation in multiferroic GdMn2O5

Abstract

It was generally accepted until recently that multiferroics RMn₂O₅ crystallized in the centrosymmetric space group Pbam and ferroelectricity in them could exist only at low temperatures due to the magnetic exchange striction. Recent comprehensive structural studies [V. Baledent et al., Phys. Rev. Lett. 114, 117601 (2015)] have shown that the actual symmetry of RMn₂O₅ at room temperature is a noncentrosymmetric monoclinic space group Pm, which allows room temperature ferroelectricity to exist. However, such a polarization has not yet been found. Our electric polarization loop studies of GdMn₂O₅ have revealed that a polarization does exist up to room temperature. This polarization occurs mainly in restricted polar domains that arise in the initial GdMn₂O₅ matrix due to phase separation and charge carrier self-organization. These domains are selfconsistent with the matrix, which leads to the noncentrosymmetricity of the entire crystal. The polarization is controlled by a magnetic field, thereby demonstrating the presence of magnetoelectric coupling. The lowtemperature ferroelectricity enhances the restricted polar domain polarization along the b axis.