[Depfis] Nobel de Física 2007

[Dto.Física [Difusión]. (FCEyN-UBA).]

Press Release

9 October 2007

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize 
in Physics for 2007 jointly to

Albert Fert
Unité Mixte de Physique CNRS/THALES, Université Paris-Sud, Orsay, France,

and

Peter Grünberg
Forschungszentrum Jülich, Germany,

"for the discovery of Giant Magnetoresistance".

Nanotechnology gives sensitive read-out heads for compact hard disks

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.

A hard disk stores information, such as music, in the form of 
microscopically small areas magnetized 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 there-fore 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.