High pressure synthesis and physical properties of multiferroic materials with multiply-ordered perovskite structure

Perovskite is one of the most important material systems for magnetoelectric multiferroic study. However, multiferroic is not expected to occur in a cubic perovskite on account of the highly symmetric crystal structure. Besides, magnetoelectric multiferroics with large ferroelectric polarization and strong magnetoelectric coupling have not been found to occur simultaneously in a single-phase multiferroic material discovered so far, challenging to the potential applications of this kind of material. Here we briefly review two multiferroic materials with multiply-ordered perovskite structure synthesized under high pressure and high temperature conditions. In the cubic perovskite LaMn3Cr4O12, we observed spin-induced ferroelectric polarization, providing the first example where ferroelectric takes place in a cubic perovskite material. In another multiply-ordered provskite BiMn3Cr4O12, type-I and type-Ⅱ multiferroic phases successively developed when cooled. It provides a rare example where two different types of multiferroic phases occur subsequently so that both large polarization and strong magnetoelectric effect are achieved in a single-phase material. In addition, since double ferroelectric phases take place in BiMn3Cr4O12, one can obtain four different polarization states by adopting different poling procedures, thus opening up a new way for generating multifunctional spintronics and multistate storage devices.