Feb 24 2016
In 1894, Pierre Curie speculated on the “the symmetry in physical phenomena, symmetry of an electric field and a magnetic field.” Since then material scientists have working to discover a unique material that displays the coexistence of ferroelectricity and magnetism in a single compound, referred to as a multiferroic compound.
Crystal structures of paraelectric and ferroelectric phases. Credit:Sim et al.
Multiferroic materials are a type of crystalline materials, which display several distinctive properties containing a minimum of two order parameters: ferroelectric, ferroelastic, and ferro- (or antiferro-) magnetic degrees of freedom. These properties deliver an increasing number of practical and useful applications, such as sensors and memory devices. Multiferroic materials are considered common, but not much is known about their molecular properties and make-up.
An article from Sim et al. provides an in depth review of the multiferroic properties and structure of RMnO3 – a hexagonal rare-earth manganite consisting of magnetic and ferroelectric orders. Several unique properties of multiferroics are formed as a result of the powerful interaction between the orders. The review explains multiferroic materials with ferroelectric and antiferromagnetic orders. A commentary about this review has also been commissioned [Pirogov (2016), Acta Cryst. B72, 1-2; doi: 10.1107/S2052520616001062].
Over the past decade an increasing number of studies have been performed in this field resulting in an expansion of the list of materials displaying multiferroic behavior in comparison with the few that were analyzed in Russia in the 1960s. This innovative research carried out in the field of multiferroic physics provides a delayed justification to the previous pioneering theoretical studies, and considering the speed of the current study it is predicted to continue into the 21st century.