Ferroelectricity from iron valence ordering in rare earth ferrites?

Abstract

The possibility of multiferroicity arising from charge ordering in LuFe2O4 and structurally related rare earth ferrites is reviewed. Recent experimental work on macroscopic indications of ferroelectricity and microscopic determination of coupled spin and charge order indicates that this scenario does not hold. Understanding the origin of the experimentally observed charge and spin order will require further theoretical work. Other aspects of recent research in these materials, such as geometrical frustration effects, possible electric-field-induced transitions, or orbital order are also briefly treated.

18 pages, 16 figures; invited Review@RRL, published version has many figures in significantly higher quality; early view accessible via DOI, assigned to issue 7