science and technology that harnesses the spin state of
in addition to the electrical charge state to store data or perform calculations. The spin of an electron is a property that makes the electron act like a tiny magnet. This property—detected as a weak magnetic force—can be used to encode information in electronic circuits, computers, and similar electronic devices. Conventional
on the other hand ignores these spins and instead employs the accumulation or movement of electrons (or other carriers of electric charge, especially
devices) to encode information.
The first major breakthrough in spintronics was the discovery of the
(GMR) effect in 1988. Working independently, Albert
in France and Peter
in Germany found that in a material consisting of alternating layers of magnetic and nonmagnetic atoms a very small change in a magnetic field can produce a large change in electrical resistance. Employing advances in nanotechnology (see under
), they used chemical techniques that allowed them to make layers of different materials that were only a few atoms thick. The GMR effect was used in the development of data-storage devices that were physically smaller but allowed increasingly denser packing of the information content. The first commercial devices using the GMR effect, produced in 1997, had a 40-fold increase in data density when compared with conventional electronics. The technology is now used in computer storage, personal music players, cell phones, and other devices that benefit from the increased size of readable memory. In a more sensitive effect, called
(TMR), an insulating material acts as a sandwich. Electrons can move through the sandwich by quantum
. Another spintronic breakthrough product is magnetoresistive memory (MRAM), which uses electron spin to store information while requiring less power than coventional magnetic storage technologies, it combines the density of DRAM (dynamic random access memory) with the speed of SRAM (static random access memory) and the nonvolatility of flash memory. In recognition of their contributions, Fert and Grünberg shared the 2007 Nobel Prize in physics.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.
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