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Magnetoresistive
Magnetoresistance is the tendency of a material (often ferromagnetic) to change the value of its electrical resistance in an externally-applied magnetic field. There are a variety of effects that can be called magnetoresistance. Some occur in bulk non-magnetic metals and semiconductors, such as geometrical magnetoresistance, Shubnikov–de Haas oscillations, or the common positive magnetoresistance in metals. Other effects occur in magnetic metals, such as negative magnetoresistance in ferromagnets or anisotropic magnetoresistance (AMR). Finally, in multicomponent or multilayer systems (e.g. magnetic tunnel junctions), giant magnetoresistance (GMR), tunnel magnetoresistance (TMR), colossal magnetoresistance (CMR), and extraordinary magnetoresistance (EMR) can be observed. The first magnetoresistive effect was discovered in 1856 by William Thomson, better known as Lord Kelvin, but he was unable to lower the electrical resistance of anything by more than 5%. Today, systems inclu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barber Pole
A barber's pole is a type of sign used by barbers to signify the place or shop where they perform their craft. The trade sign is, by a tradition dating back to the Middle Ages, a staff or pole with a helix of colored stripes (often red and white in many countries, but usually red, white and blue in the United States). The pole may be stationary or may rotate, often with the aid of an electric motor. A "barber's pole" with a helical stripe is a familiar sight, and is used as a secondary metaphor to describe objects in many other contexts. For example, if the shaft or tower of a lighthouse has been painted with a helical stripe as a daymark, the lighthouse could be described as having been painted in "barber's pole" colors. Origin in barbering and surgery During medieval times, barbers performed surgery on customers, as well as tooth extractions. The original pole had a brass wash basin at the top (representing the vessel in which leeches were kept) and bottom (representi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tunnel Magnetoresistance
Tunnel magnetoresistance (TMR) is a magnetoresistive effect that occurs in a magnetic tunnel junction (MTJ), which is a component consisting of two ferromagnets separated by a thin insulator. If the insulating layer is thin enough (typically a few nanometres), electrons can tunnel from one ferromagnet into the other. Since this process is forbidden in classical physics, the tunnel magnetoresistance is a strictly quantum mechanical phenomenon. Magnetic tunnel junctions are manufactured in thin film technology. On an industrial scale the film deposition is done by magnetron sputter deposition; on a laboratory scale molecular beam epitaxy, pulsed laser deposition and electron beam physical vapor deposition are also utilized. The junctions are prepared by photolithography. Phenomenological description The direction of the two magnetizations of the ferromagnetic films can be switched individually by an external magnetic field. If the magnetizations are in a parallel orientation it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tunnel Magnetoresistance
Tunnel magnetoresistance (TMR) is a magnetoresistive effect that occurs in a magnetic tunnel junction (MTJ), which is a component consisting of two ferromagnets separated by a thin insulator. If the insulating layer is thin enough (typically a few nanometres), electrons can tunnel from one ferromagnet into the other. Since this process is forbidden in classical physics, the tunnel magnetoresistance is a strictly quantum mechanical phenomenon. Magnetic tunnel junctions are manufactured in thin film technology. On an industrial scale the film deposition is done by magnetron sputter deposition; on a laboratory scale molecular beam epitaxy, pulsed laser deposition and electron beam physical vapor deposition are also utilized. The junctions are prepared by photolithography. Phenomenological description The direction of the two magnetizations of the ferromagnetic films can be switched individually by an external magnetic field. If the magnetizations are in a parallel orientation it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peter Grünberg
Peter Andreas Grünberg (; 18 May 1939 – 7 April 2018) was a German physicist, and Nobel Prize in Physics laureate for his discovery with Albert Fert of giant magnetoresistance which brought about a breakthrough in gigabyte hard disk drives. Life and career Grünberg was born in Pilsen, Bohemia—which at the time was in the German-occupied Protectorate of Bohemia and Moravia (now the Czech Republic)—to the Sudeten German family of Anna and Feodor A. Grünberg which first lived in Dysina (Dýšina) to the east of Pilsen. Grünberg was a Catholic. After the war, the family was interned; the parents were brought to a camp. His father, a Russia-born engineer who since 1928 had worked for Škoda, died on 27 November 1945 in Czech imprisonment and is buried in a mass grave in Pilsen which is also inscribed with ''Grünberg Theodor † 27. November 1945''. His mother Anna (who died in 2002 aged 100) had to work in agriculture and stayed with her parents in the Petermann ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Giant Magnetoresistance
Giant magnetoresistance (GMR) is a quantum mechanical magnetoresistance effect observed in multilayers composed of alternating ferromagnetic and non-magnetic conductive layers. The 2007 Nobel Prize in Physics was awarded to Albert Fert and Peter Grünberg for the discovery of GMR. The effect is observed as a significant change in the electrical resistance depending on whether the magnetization of adjacent ferromagnetic layers are in a parallel or an antiparallel alignment. The overall resistance is relatively low for parallel alignment and relatively high for antiparallel alignment. The magnetization direction can be controlled, for example, by applying an external magnetic field. The effect is based on the dependence of electron scattering on spin orientation. The main application of GMR is in magnetic field sensors, which are used to read data in hard disk drives, biosensors, microelectromechanical systems (MEMS) and other devices. GMR multilayer structures are also used in m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Giant Magnetoresistance
Giant magnetoresistance (GMR) is a quantum mechanical magnetoresistance effect observed in multilayers composed of alternating ferromagnetic and non-magnetic conductive layers. The 2007 Nobel Prize in Physics was awarded to Albert Fert and Peter Grünberg for the discovery of GMR. The effect is observed as a significant change in the electrical resistance depending on whether the magnetization of adjacent ferromagnetic layers are in a parallel or an antiparallel alignment. The overall resistance is relatively low for parallel alignment and relatively high for antiparallel alignment. The magnetization direction can be controlled, for example, by applying an external magnetic field. The effect is based on the dependence of electron scattering on spin orientation. The main application of GMR is in magnetic field sensors, which are used to read data in hard disk drives, biosensors, microelectromechanical systems (MEMS) and other devices. GMR multilayer structures are also used in m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colossal Magnetoresistance
Colossal magnetoresistance (CMR) is a property of some materials, mostly manganese-based perovskite oxides, that enables them to dramatically change their electrical resistance in the presence of a magnetic field. The magnetoresistance of conventional materials enables changes in resistance of up to 5%, but materials featuring CMR may demonstrate resistance changes by orders of magnitude. This technology may find uses in disk read-and-write heads, allowing for increases in hard disk drive data density. However, so far it has not led to practical applications because it requires low temperatures and bulky equipment. History Initially discovered in mixed-valence perovskite manganites in the 1950s by G. H. Jonker and J. H. van Santen, a first theoretical description in terms of the double-exchange mechanism was given early on. In this model, the spin orientation of adjacent Mn moments is associated with kinetic exchange of eg-electrons. Consequently, alignment o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Albert Fert
Albert Fert (; born 7 March 1938) is a French physicist and one of the discoverers of giant magnetoresistance which brought about a breakthrough in gigabyte hard disks. Currently, he is an emeritus professor at Paris-Saclay University in Orsay, scientific director of a joint laboratory (''Unité mixte de recherche'') between the Centre national de la recherche scientifique (National Scientific Research Centre) and Thales Group, and adjunct professor at Michigan State University. He was awarded the 2007 Nobel Prize in Physics together with Peter Grünberg. Biography In 1962 Albert Fert graduated from the École Normale Supérieure in Paris, where he attended courses by the physicists Alfred Kastler and Jacques Friedel. (As an undergraduate he had strong interests in photography and cinema, and was a great admirer of the work of Ingmar Bergman).) After the École Normale Supérieure, Fert attended the University of Grenoble and in 1963 received his Ph.D. (''doctorat de troisiè ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Honeywell
Honeywell International Inc. is an American publicly traded, multinational conglomerate corporation headquartered in Charlotte, North Carolina. It primarily operates in four areas of business: aerospace, building technologies, performance materials and technologies (PMT), and safety and productivity solutions (SPS). Honeywell is a Fortune 100 company, ranked 94th in 2021. In 2021 the corporation had a global workforce of approximately 99,000 employees, down from 113,000 in 2019. The current chairman and chief executive officer (CEO) is Darius Adamczyk. The corporation's current name, Honeywell International Inc., is a product of the merger of Honeywell Inc. and AlliedSignal in 1999. The corporation headquarters were consolidated with AlliedSignal's headquarters in Morristown, New Jersey; however, the combined company chose the name "Honeywell" because of the considerable brand recognition. Honeywell was a component of the Dow Jones Industrial Average index from 1999 to 200 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compass
A compass is a device that shows the cardinal directions used for navigation and geographic orientation. It commonly consists of a magnetized needle or other element, such as a compass card or compass rose, which can pivot to align itself with magnetic north. Other methods may be used, including gyroscopes, magnetometers, and GPS receivers. Compasses often show angles in degrees: north corresponds to 0°, and the angles increase clockwise, so east is 90°, south is 180°, and west is 270°. These numbers allow the compass to show azimuths or bearings which are commonly stated in degrees. If local variation between magnetic north and true north is known, then direction of magnetic north also gives direction of true north. Among the Four Great Inventions, the magnetic compass was first invented as a device for divination as early as the Chinese Han Dynasty (since c. 206 BC),Li Shu-hua, p. 176 and later adopted for navigation by the Song Dynasty Chinese during the 11th centur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indium Antimonide
Indium antimonide (InSb) is a crystalline compound made from the elements indium (In) and antimony (Sb). It is a narrow- gap semiconductor material from the III- V group used in infrared detectors, including thermal imaging cameras, FLIR systems, infrared homing missile guidance systems, and in infrared astronomy. The indium antimonide detectors are sensitive between 1–5 μm wavelengths. Indium antimonide was a very common detector in the old, single-detector mechanically scanned thermal imaging systems. Another application is as a terahertz radiation source as it is a strong photo-Dember emitter. History The intermetallic compound was first reported by Liu and Peretti in 1951, who gave its homogeneity range, structure type, and lattice constant. Polycrystalline ingots of InSb were prepared by Heinrich Welker in 1952, although they were not very pure by today's semiconductor standards. Welker was interested in systematically studying the semiconducting properties of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permalloy
Permalloy is a nickel–iron magnetic alloy, with about 80% nickel and 20% iron content. Invented in 1914 by physicist Gustav Elmen at Bell Telephone Laboratories, it is notable for its very high magnetic permeability, which makes it useful as a magnetic core material in electrical and electronic equipment, and also in magnetic shielding to block magnetic fields. Commercial permalloy alloys typically have relative permeability of around 100,000, compared to several thousand for ordinary steel. In addition to high permeability, its other magnetic properties are low coercivity, near zero magnetostriction, and significant anisotropic magnetoresistance. The low magnetostriction is critical for industrial applications, allowing it to be used in thin films where variable stresses would otherwise cause a ruinously large variation in magnetic properties. Permalloy's electrical resistivity can vary as much as 5% depending on the strength and the direction of an applied magnetic field. P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
