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Magnetoresistance
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] |
Giant Magnetoresistance
Giant magnetoresistance (GMR) is a quantum mechanics, 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, which also sets the foundation for the study of spintronics. 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 (electronics), 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, biosens ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tunnel Magnetoresistance
Tunnel magnetoresistance (TMR) is a magnetoresistance, magnetoresistive effect that occurs in a magnetic tunnel junction (MTJ), which is a component consisting of two ferromagnets separated by a thin Insulator (electrical), insulator. If the insulating layer is thin enough (typically a few nanometres), electrons can Quantum tunneling, tunnel from one ferromagnet into the other. Since this process is forbidden in classical physics, the tunnel magnetoresistance is a strictly Quantum mechanics, quantum mechanical phenomenon, and lies in the study of spintronics. 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 film ... [...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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extraordinary Magnetoresistance
Extraordinary magnetoresistance (EMR) is a geometrical magnetoresistance 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 ... effect discovered in 2000, where the change in electrical resistance upon the application of a large magnetic field can be greater than 1,000,000% at room temperature (orders of magnitude greater than other magnetoresistance effects such as GMR and CMR). The effect occurs in semiconductor-metal hybrid systems when a transverse magnetic field is applied. Without a magnetic field the system is in a low-resistance state with most of the current flow directed through the metallic region. Upon the application of a large magnetic field the system switches to a state of much higher electrical resistance, due to the Hall angle approaching 90°, with the current flow ... [...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 Plzeň, Czechoslovakia, which at the time was known as Pilsen in the German-occupied Protectorate of Bohemia and Moravia (now the Czech Republic) to the Sudeten German family of Anna and Feodor A. Grünberg. They first lived in Dýšina to the east of Plzeň. 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 Plzeň 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 th ... [...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 troi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AMR Of Permalloy
Amr or AMR may refer to: Science, environment and medicine * Antimicrobial resistance, of microorganisms (bacteria, viruses, parasites) to antimicrobials * Anisotropic magnetoresistance, resistance varying with magnetic field * Accelerating Moment Release, an earthquake precursor * Advanced Modular Reactor, a proposed Small modular reactor design Information technology * Abstract Meaning Representation, a semantic annotation framework for natural language text * Audio/modem riser, on a computer motherboard * Adaptive Multi-Rate audio codec for speech coding * Adaptive mesh refinement in numerical analysis * AMR radiotelephone network (Czechoslovakia) (in Czech, Automatizovaný městský radiotelefon) * Automatic meter reading, for utility meters * Autonomous mobile robot, portable robots used in industrial applications Companies * Abbingdon Music Research, a UK audio manufacturer * American Medical Response, a private ambulance operator * AMR Corporation, former parent c ... [...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. Indium antimonide detectors are sensitive to infrared wavelengths between 1 and 5 μm. 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 p ... [...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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shubnikov–de Haas Effect
An oscillation in the Electrical conductivity, conductivity of a material that occurs at low temperatures in the presence of very intense magnetic fields, the Shubnikov–de Haas effect (SdH) is a macroscopic manifestation of the inherent quantum mechanical nature of matter. It is often used to determine the Effective mass (solid-state physics), effective mass of charge carriers (electrons and electron holes), allowing investigators to distinguish among majority carrier, majority and minority carrier populations. The effect is named after Wander Johannes de Haas and Lev Shubnikov. Physical process At sufficiently low temperatures and high magnetic fields, the free electrons in the conduction band of a metal, semimetal, or narrow band gap semiconductor will behave like simple harmonic oscillators. When the magnetic field strength is changed, the oscillation period of the simple harmonic oscillators changes proportionally. The resulting energy spectrum is made up of Landau quantiz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
