In physics, a ferrimagnetic material is one in which the magnetic moment of the atoms on different sublattices are opposed, as in antiferromagnetism; however, in ferrimagnetic materials, the opposing moments are unequal and a spontaneous magnetization remains. Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. In Physics, Astronomy, Chemistry, and Electrical engineering, the term magnetic moment of a system (such as a loop of Electric current In materials that exhibit antiferromagnetism, the magnetic moments of atoms or molecules usuallyrelated to the spins of Electrons align in a regular pattern with neighboring This happens when the sublattices consist of different materials or ions (such as Fe2+ and Fe3+). An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge
Ferrimagnetic materials are like ferromagnets in that they hold a spontaneous magnetization below the Curie temperature, and show no magnetic order (are paramagnetic) above this temperature. Ferromagnetism is the basic mechanism by which certain materials (such as Iron) form Permanent magnets and/or exhibit strong interactions with Magnets it The Curie point ( Tc) or Curie temperature, is a term in Physics and Materials science, named after Pierre Curie (1859-1906 Paramagnetism is a form of magnetism which occurs only in the presence of an externally applied magnetic field However, there is sometimes a temperature below the Curie temperature at which the two sublattices have equal moments, resulting in a net magnetic moment of zero; this is called the magnetization compensation point. In Physics, Astronomy, Chemistry, and Electrical engineering, the term magnetic moment of a system (such as a loop of Electric current This compensation point is observed easily in garnets and rare earth - transition metal alloys (RE-TM). The garnet group includes a group of minerals that have been used since the Bronze Age as gemstones and abrasives Furthermore, ferrimagnets may also exhibit an angular momentum compensation point at which the angular momentum of the magnetic sublattices is compensated. This compensation point is a crucial point for achieving high speed magnetization reversal in magnetic memory devices*.
Ferrimagnetism is exhibited by ferrites and magnetic garnets. The oldest-known magnetic substance, magnetite (iron(II,III) oxide; Fe3O4), is a ferrimagnet; it was originally classified as a ferromagnet before Néel's discovery of ferrimagnetism and antiferromagnetism. Magnetite is not to be confused with Magnesite or Maghemite. Magnetite is a ferrimagnetic Mineral with chemical Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Louis Eugène Félix Néel ( November 22, 1904 &ndash November 17, 2000) was a French Physicist born in Lyon
Some ferrimagnetic materials are YIG (yttrium iron garnet) and ferrites composed of iron oxides and other elements such as aluminum, cobalt, nickel, manganese and zinc.
Properties
Ferrimagnetic materials have high resistivity and have anisotropic properties. The anisotropy is actually induced by an external applied field. When this applied field aligns with the magnetic dipoles it causes a net magnetic dipole moment and causes the magnetic dipoles to precess at a frequency controlled by the applied field, called Larmor or precession frequency. In Physics, Larmor precession (named after Joseph Larmor) refers to the Precession of the Magnetic moments of Electrons atomic In Physics, Larmor precession (named after Joseph Larmor) refers to the Precession of the Magnetic moments of Electrons atomic As a particular example, a microwave signal circularly polarized in the same direction as this precession strongly interacts with the magnetic dipole moments; when it is polarized in the opposite direction the interaction is very low. Microwaves are electromagnetic waves with Wavelengths ranging from 1 mm to 1 m or frequencies between 0 Polarization ( ''Brit'' polarisation) is a property of Waves that describes the orientation of their oscillations In Physics, Astronomy, Chemistry, and Electrical engineering, the term magnetic moment of a system (such as a loop of Electric current When the interaction is strong the microwave signal can pass through the material. This directional property is used in the construction of microwave devices like isolators, circulators and gyrators. See also Optical circulator A circulator is a passive Electronic component with three or more ports in which the ports can be accessed in such a way that when The gyrator or positive impedance inverter is an Electric circuit which inverts an impedance.
References
- C. D. Stanciu, A. V. Kimel, F. Hansteen, A. Tsukamoto, A. Itoh, A. Kirilyuk, and Th. Rasing, Ultrafast spin dynamics across compensation points in ferrimagnetic GdFeCo: The role of angular momentum compensation, Phys. Rev. B 73, 220402(R) (2006).
Dictionary
ferrimagnetism
-noun
- (physics) a form of antiferromagnetism in which some magnetization remains below a critical temperature (the Neel temperature)
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