Nobel Prize in Physics 2007 – “for the discovery of Giant Magnetoresistance“: Albert Fert and Peter Grünberg. ‘This year’s physics prize is awarded for the technology that is used to read data on hard disks. It is thanks to this technology that it has been possible to miniaturize hard disks so radically in recent years. Sensitive read-out heads are needed to be able to read data from the compact hard disks used in laptops and some music players, for instance.
In 1988 the Frenchman Albert Fert and the German Peter Grünberg each independently discovered a totally new physical effect: Giant Magnetoresistance or GMR. Very weak magnetic changes give rise to major differences in electrical resistance in a GMR system. A system of this kind is the perfect tool for reading data from hard disks when information registered magnetically has to be converted to electric current. Soon researchers and engineers began work to enable use of the effect in read-out heads. In 1997 the first read-out head based on the GMR effect was launched and this soon became the standard technology. Even the most recent read-out techniques of today are further developments of GMR.’
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The Giant Magnetoresistive Head: A giant leap for IBM Research. ‘The “giant magnetoresistive” (GMR) effect was discovered in the late 1980s by two European scientists working independently: Peter Grünberg of the KFA research institute in Jülich, Germany, and Albert Fert of the University of Paris-Sud . They saw very large resistance changes – 6 percent and 50 percent, respectively – in materials comprised of alternating very thin layers of various metallic elements. This discovery took the scientific community by surprise; physicists did not widely believe that such an effect was physically possible. These experiments were performed at low temperatures and in the presence of very high magnetic fields and used laboriously grown materials that cannot be mass-produced, but the magnitude of this discovery sent scientists around the world on a mission to see how they might be able to harness the power of the Giant Magnetoresistive effect.’
Applications of Giant Magnetoresistance. ‘Giant magnetoresistance (GMR) already has magnetic appeal: It allows more data to be packed on computer disks. If improvements are made in the interfaces between magnetic layers in thin-film structures, the number of new applications could prove irresistible.’
An overview of Giant Magnetoresistance (GMR) by Evgeny Tsymbal, University of Nebraska-Lincoln.