Ferroelectricity and Magnetism

Ferroelectrics may And application in magnetoelectric devices, either in combination with magnetic materials or intrinsically as a multiferroic material. The latter represents a rare class of materials that are both ferroelectric and ferromagnetic, and often also ferroelastic, in the same phase [113]. This means that, simultaneously, they can undergo spontaneous polarization, magnetization, and deformation that can be reoriented by the respective application of an electric or magnetic fleld, or by 

In composite materials, the ME can be achieved as a result of the elastic interaction between piezoelectric or electrostrictive and piezomagnetic or magnetostrictive phases which, independently, may have no ME. Thus, as a product property of the composite, the ME can be described as [126]  

Among perovskites there are two examples that combine ferroelectric and magnetic properties in one phase, namely BiMn03 and BiFe03. Although, both of these materials contain a non-empty d-shell of the B-site cation, it is noteworthy that the ferroelectric ordering occurs in these perovskites due rather to the A-site than to the B-site cation off-shift [141]. 

In concluding this section, it is important to note that investigations of the correlation between ferroelectricity and magnetism represents a rapidly developing 

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An overview of the atomistic and electronic phenomena utilized in electroceramic technology is given in Figure 3. More detailed discussions of compositional families and stmcture—property relationships can be found in other articles. (See for example, Ferroelectrics and Magnetic materials.)... 

In this Chapter, contrary to Chaps. 2 and 3, where primary ferroics were considered, we are going to pay more attention to multiferroics with coexistence of ferroelectric and magnetic order. We will consider these multiferroics in the form of thin films on subsfrate [9, 10] or nanowires [11] on the example of quantum paraelectric EuTiOs. The necessity of detailed consideration of magnetoelectric effects in such systems is pretty obvious also. 

Multiferroic materials exhibits both ferroelectric and magnetic in nature and have much attracted research interest due to their potential application in multistate data storage and electric field controlled spintronics. Among all the studies related to the materials, transition metal oxides with perovskite structure are noteworthy [22,26]. 

In the broad range of ceramic materials that are used for electrical and electronic apphcations, each category of material exhibits unique property characteristics which directiy reflect composition, processing, and microstmcture. Detailed treatment is given primarily to those property characteristics relating to insulation behavior and electrical conduction processes. Further details concerning the more specialized electrical behavior in ceramic materials, eg, polarization, dielectric, ferroelectric, piezoelectric, electrooptic, and magnetic phenomena, are covered in References 1—9. 

The main categories of electrical/optical ceramics are as follows phosphors for TV, radar and oscilloscope screens voltage-dependent and thermally sensitive resistors dielectrics, including ferroelectrics piezoelectric materials, again including ferroelectrics pyroelectric ceramics electro-optic ceramics and magnetic ceramics. 

Blinc R (2007) Order and Disorder in Perovskites and Relaxor Ferroelectrics. 124 51-67 Boca R (2005) Magnetic Parameters and Magnetic Functions in Mononuclear Complexes Beyond the Spin-Hamiltonian Formalism 117 1-268 Bohrer D, see Schetinger MRC (2003) 104 99-138 Bonnet S, see Baranoff E (2007) 123 41-78... 

Barium titanate has many important commercial apphcations. It has both ferroelectric and piezoelectric properties. Also, it has a very high dielectric constant (about 1,000 times that of water). The compound has five crystalline modifications, each of which is stable over a particular temperature range. Ceramic bodies of barium titanate find wide applications in dielectric amplifiers, magnetic amplifiers, and capacitors. These storage devices are used in digital calculators, radio and television sets, ultrasonic apparatus, crystal microphone and telephone, sonar equipment, and many other electronic devices. 

FERROELECTRIC MATERIALS. The dielectric analogs of ferromagnetic materials. Their uses parallel those of ferromagnetic materials in such applications as magnetostriclive transducers, magnetic amplifiers, and magnetic information storage devices. Rochelle salt was the first ferroelectric material to be discovered and the barium titanale ceramics arc materials of this type... 

Recently Frohlich has extended his ideas to give a possible explanation of the extraordinary high sensitivity of certain biological systems to very weak external electric and magnetic signals (2). The model is a combination of both, a nonlinear chemical reaction, which is based on long range interactions, and a ferroelectric term, which represent the specific dielectric properties of membranes. The model equations read ... 

Liquid crystals are interesting supramolecular systems which can show second harmonic generation when they are aligned appropriately. Ferroelectric LCs [250] as well as bent-core molecules have been used to this purpose, and show reasonable second harmonic generation [251]. These materials combine non-linear optical effects with simple processing procedures on account of their liquid crystalline flow characteristics and the possibility of organising them with electric and magnetic fields. 

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