title: Bond- versus site-centred ordering and possible ferroelectricity in manganites.
abstract: Transition metal oxides with a perovskite-type structure constitute a large group of compounds with interesting properties. Among them are materials such as the prototypical ferroelectric system BaTiO(3), colossal magnetoresistance manganites and the high-T(c) superconductors. Hundreds of these compounds are magnetic, and hundreds of others are ferroelectric, but these properties very seldom coexist. Compounds with an interdependence of magnetism and ferroelectricity could be very useful: they would open up a plethora of new applications, such as switching of magnetic memory elements by electric fields. Here, we report on a possible way to avoid this incompatibility, and show that in charge-ordered and orbitally ordered perovskites it is possible to make use of the coupling between magnetic and charge ordering to obtain ferroelectric magnets. In particular, in manganites that are less than half doped there is a type of charge ordering that is intermediate between site-centred and bond-centred. Such a state breaks inversion symmetry and is predicted to be magnetic and ferroelectric.
authors.affiliation: Laboratory of Solid State Physics, Material Science Center, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
authors.forename: Dmitry V
authors.initials: DV
authors.lastname: Efremov
authors.forename: Jeroen
authors.initials: J
authors.lastname: van den Brink
authors.forename: Daniel I
authors.initials: DI
authors.lastname: Khomskii
mesh_terms: D003198:Computer Simulation; D003460:Crystallization / Q000379:methods*; D004560:Electricity; D004563:Electrochemistry; D004581:Electronics; D016247:Information Storage and Retrieval; D008280:Magnetics / Q000295:instrumentation*; D017895:Manganese Compounds / Q000737:chemistry*; D008420:Manufactured Materials; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation
chemical_list: D017895:Manganese Compounds; C494384:manganite