Room-Temperature Antiferroelectricity in Multiferroic Hexagonal Rare-Earth Ferrites.

The antiferroelectric (AFE) phase, in which nonpolar and polar states are switchable by an electric field, is a recent discovery in promising multiferroics of hexagonal rare-earth manganites (ferrites), -Mn(Fe)O. However, this phase has so far only been observed at 60-160 K, which restricts key investigations into the microstructures and magnetoelectric behaviors. Herein, we report the successful expansion of the AFE temperature range (10-300 K) by preparing -DyFeO films through epitaxial stabilization. Room-temperature scanning transmission electron microscopy reveals that the AFE phase originates from a nanomosaic structure comprising AFE 3̅1 and ferroelectric 6 domains with small domain sizes of 1-10 nm. The nanomosaic structure is stabilized by a low / ratio derived from the large ionic radius of Dy. Furthermore, weak ferromagnetism and magnetocapacitance behaviors are observed. Below 10 K, the film exhibits an M-shaped magnetocapacitance versus magnetic field curve, indicating unusual magnetoelectric coupling in the AFE phase.