Multiferroic

CHARGE ORDERING AND TILT MODULATION IN MULTIFERROIC FLUORIDES WITH TTB STRUCTURE BY ELECTRON DIFFRACTION AND SINGLE CRYSTAL XRD... 

Charge Ordering and Tilt Modulation in Multiferroic Fluorides... 

S.Fabbrici, E.Montanaii, G.Calestani and A. Migliori Charge ordering and tilt modulation in multiferroic KxM"xM "i xF3 (0.4transition metal fluorides with tetragonal tungsten bronze structure Chem. Mater. 2004 16(16) 3007-3019... 

If we can combine ferroelectrically polarizable guest molecules with PCPMs, then we can obtain new types of multiferroic materials, where ferroelectricity and ferromagnetism coexist. Such multifunctional materials have recently aroused increasing interest from the viewpoint of the development of new materials with very large magnetoelectric effects. [Mn3(HCOO)6] EtOH is considered to be the first ferroelectric PCP.182 Because the desolvated compound [Mn3(HCOO)6] shows a very small and almost temperature-independent dielectric constant, irrespective of the direction of the electric field,183 the observed ferroelectric property is considered to come mainly from the guest EtOH molecules. 

Multiferroics constitute an important area of materials research.7 Multiferroics are materials which are magnetic as well as ferroelectric. In principle, these two properties cannot occur together since one requires the presence of ri-electrons and the other does not. Strategies to attain multiferroic properties in oxides are presented in an article. 

Besides a range of possible device applications, the science of these materials is truly fascinating.1-6 In the most general terms, multiferroics are materials in which ferromagnetism, ferroelectricity and feiToelasticity occur in the same... 

Another area that has been of interest since the development of this field is that of metal oxides. Simple metal oxides such as MgO provide a test bed for new methods. More complex oxides have attracted much interest for their commercially important properties—solid electrolytes, ferroelectrics, catalysts, semiconductors, superconductors, multiferroics. Relatively simple calculations can, for example, track the path of ions through ionic conductors and suggest alternative solids for fuel cells or batteries. Solids with interesting electrical and magnetic properties such as high Tc superconductors and solids showing colossal magnetoresistance (CMR) have been... 

We are also interested in magnetoelectrics which form an important subgroup of multiferroics. Magnetoelectrics exhibit, simultaneously, ferromagnetic and ferroelectric properties, the combination of which is expected to revolutionize computers. A memory element combining both properties would permit an electric write operation combined with a magnetic read, eliminating the need... 

In the layered Ruddlesden-Popper and Dion-Jacobson phases, improper ferroelectricity can also arise in a form termed hybrid improper ferroelectricity. Here, the ferroelectricity arises when two non-polar rotations of BO octahedra combine to produce a polar stmcture. The same effect may well also occur in the Aurivillius phases although this has not yet been proven. The creation of improper ferroelectric polarisation due to magnetic interactions in multiferroic perovskites is described in Section 7.10. 

Ferroic is a generic term for crystals that have an internal structure that can be switched from one stable orientation to another that is equally stable, by the application of a suitable driving force along an appropriate direction. Multiferroics are... 

---