Multiferroicity due to charge ordering
نویسندگان
چکیده
In this contribution to the special issue on multiferroics we focus on multiferroicity driven by different forms of charge ordering. We will present the generic mechanisms by which charge ordering can induce ferroelectricity in magnetic systems. There is a number of specific classes of materials for which this is relevant. We will discuss in some detail (i) the perovskite manganites of the type (PrCa)MnO3, (ii) the complex and interesting situation in magnetite Fe3O4, (iii) the newly discovered strongly ferroelectric frustrated LuFe2O4, (iv) an example of a quasi one-dimensional organic system. All these are “type-I” multiferroics, in which ferroelectricity and magnetism have different origin and occur at different temperatures. In the second part of this review we discuss “type-II” multiferroics, in which ferroelectricity is completely due to magnetism, but with charge ordering playing important role, such as (v) the newly-discovered multiferroic Ca3CoMnO6, (vi) possible ferroelectricity in rare earth perovskite nickelates of the type RNiO3, the multiferroic properties of (vii) manganites of the type RMn2O5, (viii) perovskite manganites with magnetic E-type ordering and (ix) bilayer manganites. PACS numbers: 75.47.Lx, 71.10.-w, 71.27.+a, 71.45.Gm ar X iv :0 80 3. 29 64 v2 [ co nd -m at .m tr lsc i] 2 4 A pr 2 00 8 Multiferroicity due to charge ordering 2
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