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2007年度诺贝尔物理奖---巨磁电阻效应
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中新网10月9日电 瑞典皇家科学院诺贝尔奖委员会今天宣布，将2007年度诺贝尔物理奖授予法国科学家艾尔伯-费尔和德国科学家皮特-克鲁伯格，以表彰他们发现巨磁电阻效应的贡献。 [ Last edited by lilywxm on 2007-10-9 at 18:30 ] |
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2楼2007-10-09 18:32:46
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网易的报道很××：根据这一效应开发的小型大容量计算机硬盘已得到广泛应用。 我就想不通怎么是造硬盘了... for technology used to read information from computer hard drives(美联社) GMR：A very large decrease in electrical resistance upon application of a magnetic field in certain structures composed of alternating layers of magnetic and nonmagnetic metals. GMR EFFECT: The effect manifests itself as a significant decrease in resistance from the zero-field state, when the magnetization of adjacent ferromagnetic layers are antiparallel due to a weak anti-ferromagnetic coupling between layers, to a lower level of resistance when the magnetization of the adjacent layers align due to an applied external field. The spin of the electrons of the nonmagnetic metal align parallel or antiparallel with an applied magnetic field in equal numbers, and therefore suffer less magnetic scattering when the magnetizations of the ferromagnetic layers are parallel. WIKI上复制过来的 [ Last edited by goldring on 2007-10-9 at 20:32 ] |
3楼2007-10-09 20:29:34
sciencegreen
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Nobel prize recognizes GMR pioneers(zz)
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The 2007 Nobel Prize in Physics has been awarded jointly to Albert Fert of the Université Paris-Sud in France and Peter Grünberg of the Forschungszentrum Jülich in Germany "for the discovery of giant magnetoresistance". Their discovery, which both physicists made independently in 1988, led to a dramatic rise in the amount of data that can be stored on computer hard-disk drives. Fert and Grünberg share prize money totalling 10 million Swedish krone (about $1.5m). Giant magnetoresistance, or GMR, is the sudden change in electrical resistivity that occurs when a material consisting of alternating ferromagnetic and non-magnetic metal layers is exposed to a sufficiently high magnetic field. In particular, the resistance becomes much lower if the magnetization in neighbouring layers is parallel and much higher if it is antiparallel. This increase in sensitivity is due to "spin up" and "spin down" electrons scattering differently in the individual layers. GMR has since been used to develop extremely small and sensitive read heads for magnetic hard-disk drives. These have allowed an individual data bit to be stored in a much smaller area on a disk, boosting the storage capacity greatly. The first commercial read heads based on GMR were launched by IBM in 1997 and GMR is now a standard technology found in nearly all computers, digital cameras and MP3 players worldwide. In Fert's original work, he and his team studied an iron/chromium/iron trilayer system that showed an decrease in resistance of 1.5%. Grünberg and colleagues, in contrast, studied an iron/chromium multilayer system in which the electrical resistance decreased by nearly 50%. "These films started out as being very esoteric, but it turned out that they would have great practical importance," says Tony Bland, a physicist from the University of Cambridge. "They paved the way for substantial information densities of commercial disk drives. It also paved the way for new physics, such as tunneling magnetoresistance (TMR), spintronics and new sensor technology, for example biosensors. The caveat is that GMR has already become old technology and people are now interested in TMR for future technology." TMR gives rise to a more pronounced resistance change in small applied fields than is found in GMR devices. Albert Fert was born in 1938 in Carcassone, France, and received a PhD in physics in from Université Paris-Sud, Orsay in France. He is now also scientific director of CNRS/Thales Unité Mixte de Physique in Orsay. Peter Grünberg was born in 1939 in Pilsen (now in Czech Republic) and is a German citizen. He gained his PhD in physics from the Technische Universität Darmstadt, Germany. Grünberg, who holds a patent on GMR, originally submitted his paper slightly before Fert, although Fert’s was published first. "But whereas Fert was able to describe all the underlying physics, Grunberg immediately saw the technological importance," adds Bland. from http://physicsworld.com/cws/home |
4楼2007-10-10 01:47:55
