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This year's Nobel Physics prize is awarded to the technology that is used to read data on hard disks. Thanks to this technology, it has been made possible to miniaturise hard disks so radically in recent years -- making possible the existence of iPod and many such devices which uses tiny hard disks to store data.
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.
A hard disk stores information, such as music, in the form of microscopically small areas magnetised in different directions. The information is retrieved by a read-out head that scans the disk and registers the magnetic changes. The smaller and more compact the hard disk, the smaller and weaker the individual magnetic areas. More sensitive read-out heads are therefore required if information has to be packed more densely on a hard disk. A read-out head based on the GMR effect can convert very small magnetic changes into differences in electrical resistance and therefore into changes in the current emitted by the read-out head. The current is the signal from the read-out head and its different strengths represent ones and zeros.
The GMR effect was discovered thanks to new techniques developed during the 1970s to produce very thin layers of different materials. If GMR is to work, structures consisting of layers that are only a few atoms thick have to be produced. For this reason, GMR can also be considered one of the first real applications of the promising field of nanotechnology.
The discovery of GMR is also considered as the birth of spintronics. Spintronics (a neologism for 'spin-based electronics'), also known as magnetoelectronics, is an emerging technology which exploits the quantum spin states of electrons as well as making use of their charge state. The electron spin itself is manifested as a two-state magnetic energy system.
Spintronic devices are used in the field of mass-storage devices; recently (in 2002) IBM scientists announced that they could compress massive amounts of data into a small area, at approximately one trillion bits per square inch (1.5 Gbit/mm²) or roughly 1 TB on a single sided 3.5" diameter disc. The storage density of hard drives is rapidly increasing along an exponential growth curve. The doubling period for the areal density of information storage is 12 months, much shorter than Moore's Law, which observes that the number of transistors in an integrated circuit doubles every 18 months. Also the hard disk drives use a spin effect to function, the giant magnetoresistive effect.
Future applications may include a spin-based transistor which requires the development of magnetic semiconductors exhibiting room temperature ferromagnetism. The operation of MRAM or magnetic random access memory is also based on spintronic principles.
Source
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.
A hard disk stores information, such as music, in the form of microscopically small areas magnetised in different directions. The information is retrieved by a read-out head that scans the disk and registers the magnetic changes. The smaller and more compact the hard disk, the smaller and weaker the individual magnetic areas. More sensitive read-out heads are therefore required if information has to be packed more densely on a hard disk. A read-out head based on the GMR effect can convert very small magnetic changes into differences in electrical resistance and therefore into changes in the current emitted by the read-out head. The current is the signal from the read-out head and its different strengths represent ones and zeros.
The GMR effect was discovered thanks to new techniques developed during the 1970s to produce very thin layers of different materials. If GMR is to work, structures consisting of layers that are only a few atoms thick have to be produced. For this reason, GMR can also be considered one of the first real applications of the promising field of nanotechnology.
The discovery of GMR is also considered as the birth of spintronics. Spintronics (a neologism for 'spin-based electronics'), also known as magnetoelectronics, is an emerging technology which exploits the quantum spin states of electrons as well as making use of their charge state. The electron spin itself is manifested as a two-state magnetic energy system.
Spintronic devices are used in the field of mass-storage devices; recently (in 2002) IBM scientists announced that they could compress massive amounts of data into a small area, at approximately one trillion bits per square inch (1.5 Gbit/mm²) or roughly 1 TB on a single sided 3.5" diameter disc. The storage density of hard drives is rapidly increasing along an exponential growth curve. The doubling period for the areal density of information storage is 12 months, much shorter than Moore's Law, which observes that the number of transistors in an integrated circuit doubles every 18 months. Also the hard disk drives use a spin effect to function, the giant magnetoresistive effect.
Future applications may include a spin-based transistor which requires the development of magnetic semiconductors exhibiting room temperature ferromagnetism. The operation of MRAM or magnetic random access memory is also based on spintronic principles.
Source
