|
Multiferroics
Multiferroics are defined as materials that exhibit more than one of the primary ferroic properties in the same phase: * ferromagnetism – a magnetisation that is switchable by an applied magnetic field * ferroelectricity – an electric polarisation that is switchable by an applied electric field * ferroelasticity – a deformation that is switchable by an applied stress While ferroelectric ferroelastics and ferromagnetic ferroelastics are formally multiferroics, these days the term is usually used to describe the ''magnetoelectric multiferroics'' that are simultaneously ferromagnetic and ferroelectric. Sometimes the definition is expanded to include nonprimary order parameters, such as antiferromagnetism or ferrimagnetism. In addition, other types of primary order, such as ferroic arrangements of magnetoelectric multipoles of which ferrotoroidicity is an example, have also been recently proposed. Besides scientific interest in their physical properties, multiferroics have pote ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiferroics History Use Of Terms Magnetoelectric And Multiferroic
Multiferroics are defined as materials that exhibit more than one of the primary Ferroics, ferroic properties in the same phase: * ferromagnetism – a magnetisation that is switchable by an applied magnetic field * ferroelectricity – an electric polarisation that is switchable by an applied electric field * ferroelasticity – a deformation that is switchable by an applied stress While ferroelectric ferroelastics and ferromagnetic ferroelastics are formally multiferroics, these days the term is usually used to describe the ''Magnetoelectric effect#cite note-5, magnetoelectric multiferroics'' that are simultaneously ferromagnetic and ferroelectric. Sometimes the definition is expanded to include nonprimary order parameters, such as antiferromagnetism or ferrimagnetism. In addition, other types of primary order, such as ferroic arrangements of magnetoelectric multipoles of which Toroidal moment, ferrotoroidicity is an example, have also been recently proposed. Besides scientific in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferroelectrics (journal)
Ferroelectricity is a characteristic of certain materials that have a spontaneous electric polarization that can be reversed by the application of an external electric field. All ferroelectrics are also piezoelectric and pyroelectric, with the additional property that their natural electrical polarization is reversible. The term is used in analogy to ferromagnetism, in which a material exhibits a permanent magnetic moment. Ferromagnetism was already known when ferroelectricity was discovered in 1920 in Rochelle salt by Joseph Valasek.See and Thus, the prefix ''ferro'', meaning iron, was used to describe the property despite the fact that most ferroelectric materials do not contain iron. Materials that are both ferroelectric ''and'' ferromagnetic are known as multiferroics. Polarization When most materials are electrically polarized, the polarization induced, ''P'', is almost exactly proportional to the applied external electric field ''E''; so the polarization is a linear fun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferroelectricity
Ferroelectricity is a characteristic of certain materials that have a spontaneous electric polarization that can be reversed by the application of an external electric field. All ferroelectrics are also piezoelectric and pyroelectric, with the additional property that their natural electrical polarization is reversible. The term is used in analogy to ferromagnetism, in which a material exhibits a permanent magnetic moment. Ferromagnetism was already known when ferroelectricity was discovered in 1920 in Rochelle salt by Joseph Valasek.See and Thus, the prefix ''ferro'', meaning iron, was used to describe the property despite the fact that most ferroelectric materials do not contain iron. Materials that are both ferroelectric ''and'' ferromagnetic are known as multiferroics. Polarization When most materials are electrically polarized, the polarization induced, ''P'', is almost exactly proportional to the applied external electric field ''E''; so the polarization is a linear fun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bismuth Ferrite
Bismuth ferrite (BiFeO3, also commonly referred to as BFO in materials science) is an inorganic chemical compound with perovskite structure and one of the most promising multiferroic materials. The room-temperature phase of BiFeO3 is classed as rhombohedral belonging to the space group R3c. It is synthesized in bulk and thin film form and both its antiferromagnetic (G type ordering) Néel temperature (approximately 653 K) and ferroelectric Curie temperature are well above room temperature (approximately 1100K). Ferroelectric polarization occurs along the pseudocubic direction (\langle 111\rangle_c) with a magnitude of 90–95 μC/cm2. Sample Preparation Bismuth ferrite is not a naturally occurring mineral and several synthesis routes to obtain the compound have been developed. Solid state synthesis In the solid state reaction method bismuth oxide (Bi2O3) and iron oxide (Fe2O3) in a 1:1 mole ratio are mixed with a mortar or by ball milling and then fired at elevated te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bismuth Ferrite
Bismuth ferrite (BiFeO3, also commonly referred to as BFO in materials science) is an inorganic chemical compound with perovskite structure and one of the most promising multiferroic materials. The room-temperature phase of BiFeO3 is classed as rhombohedral belonging to the space group R3c. It is synthesized in bulk and thin film form and both its antiferromagnetic (G type ordering) Néel temperature (approximately 653 K) and ferroelectric Curie temperature are well above room temperature (approximately 1100K). Ferroelectric polarization occurs along the pseudocubic direction (\langle 111\rangle_c) with a magnitude of 90–95 μC/cm2. Sample Preparation Bismuth ferrite is not a naturally occurring mineral and several synthesis routes to obtain the compound have been developed. Solid state synthesis In the solid state reaction method bismuth oxide (Bi2O3) and iron oxide (Fe2O3) in a 1:1 mole ratio are mixed with a mortar or by ball milling and then fired at elevated te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetoelectric Effect
In its most general form, the magnetoelectric effect (ME) denotes any coupling between the magnetic and the electric properties of a material. The first example of such an effect was described by Wilhelm Röntgen in 1888, who found that a dielectric material moving through an electric field would become magnetized. A material where such a coupling is intrinsically present is called a magnetoelectric. Historically, the first and most studied example of this effect is the linear magnetoelectric effect. Mathematically, while the electric susceptibility \chi^e and magnetic susceptibility \chi^v describe the electric and magnetic polarization responses to an electric, resp. a magnetic field, there is also the possibility of a magnetoelectric susceptibility \alpha_ which describes a linear response of the electric polarization to a magnetic field, and vice versa: :P_i= \sum_j \epsilon_0\chi^e_ E_ + \sum_j \alpha_H_j :\mu_0 M_i= \sum_j \mu_0\chi^v_H_ + \sum_j \alpha_E_j, The tensor \alpha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nicola Spaldin
Nicola Ann Spaldin (born 1969)Nicola Spaldin's FRS is Professor of Materials Theory at ETH Zurich, known for her pioneering research on multiferroics. Education and early life A native of Sunderland, Tyne and Wear, England, Spaldin earned a Bachelor of Arts degree in Natural Sciences from the University of Cambridge in 1991, and a PhD in chemistry from the University of California, Berkeley in 1996. retrieved 2015-06-16. Career and research Spaldin was inspired to search for multiferroics, magnetic ferroelectric materials, by a remark about potential collaboration made by a colleague studying ferroelectrics during her postdoctoral research studying magnetic phenomena at Yale University from 1996 to 1997. She continued to develop the theory of these materials as a new faculty member at the University of California, Santa Barbara (UCSB), and in 2000 published (under her previous name, Hill) "a seminal article" that for the first time explained why few such materials were know ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spintronic
Spintronics (a portmanteau meaning spin transport electronics), also known as spin electronics, is the study of the intrinsic spin of the electron and its associated magnetic moment, in addition to its fundamental electronic charge, in solid-state devices. The field of spintronics concerns spin-charge coupling in metallic systems; the analogous effects in insulators fall into the field of multiferroics. Spintronics fundamentally differs from traditional electronics in that, in addition to charge state, electron spins are exploited as a further degree of freedom, with implications in the efficiency of data storage and transfer. Spintronic systems are most often realised in dilute magnetic semiconductors (DMS) and Heusler alloys and are of particular interest in the field of quantum computing and neuromorphic computing. History Spintronics emerged from discoveries in the 1980s concerning spin-dependent electron transport phenomena in solid-state devices. This includes the observ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barium Titanate
Barium titanate (BTO) is an inorganic compound with chemical formula BaTiO3. Barium titanate appears white as a powder and is transparent when prepared as large crystals. It is a Ferroelectricity, ferroelectric, Pyroelectricity, pyroelectric, and Piezoelectricity, piezoelectric ceramic material that exhibits the photorefractive effect. It is used in capacitors, electromechanical transducers and nonlinear optics. Structure The solid exists in one of four polymorphs depending on temperature. From high to low temperature, these crystal symmetries of the four polymorphs are Cubic crystal system, cubic, Tetragonal crystal system, tetragonal, Orthorhombic crystal system, orthorhombic and Trigonal crystal system, rhombohedral crystal structure. All of these phases exhibit the ferroelectric effect apart from the cubic phase. The high temperature cubic phase is easiest to describe, as it consists of regular corner-sharing octahedral TiO6 units that define a cube with O vertices and Ti- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferroics
Ferroics is the generic name given to the study of ferromagnets, ferroelectrics, and ferroelastics. Overview The basis of ferroics is to understand the large changes in physical characteristics that occur over a very narrow temperature range. The changes in physical characteristics occur when phase transitions take place around some critical temperature value, normally denoted by T_c. Above this critical temperature, the crystal is in a nonferroic state and does not exhibit the physical characteristic of interest. Upon cooling the material down below T_c it undergoes a spontaneous phase transition. Such a phase transition typically results in only a small deviation from the nonferroic crystal structure, but in altering the shape of the unit cell the point symmetry of the material is reduced. This breaking of symmetry is physically what allows the formation of the ferroic phase. In ferroelectrics, upon lowering the temperature below T_c, a spontaneous dipole moment is ind ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physical Review B
''Physical Review B: Condensed Matter and Materials Physics'' (also known as PRB) is a peer-reviewed, scientific journal, published by the American Physical Society (APS). The Editor of PRB is Laurens W. Molenkamp. It is part of the ''Physical Review'' family of journals. About the Physical Review Journals The current Editor in Chief is . PRB currently publishes over 4500 papers a year, making it one of the largest physics journals in the world. PRB ranked by the Eigenfactor, University of Washingto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relaxor Ferroelectric
Relaxor ferroelectrics are ferroelectric materials that exhibit high electrostriction. , although they have been studied for over fifty years, the mechanism for this effect is still not completely understood, and is the subject of continuing research. Examples of relaxor ferroelectrics include: * lead magnesium niobate (PMN) * lead magnesium niobate-lead titanate (PMN-PT) * lead lanthanum zirconate titanate (PLZT) * lead scandium niobate (PSN) *Barium Titanium-Bismuth Zinc Niobium Tantalum (BT-BZNT) *Barium Titanium-Barium Strontium Titanium (BT-BST) Applications Relaxor Ferroelectric materials find application in high efficiency energy storage Energy storage is the capture of energy produced at one time for use at a later time to reduce imbalances between energy demand and energy production. A device that stores energy is generally called an accumulator or battery. Energy comes in ... and conversion as they have high dielectric constants, orders-of-magnitude high ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
