[Storage-research-list] Nobel in Physics for "Giant Magnetoresistance"

[Andrew Klosterman]

This year's Nobel Prize in Physics was granted for technology used in
modern hard drives.

Chalk one up for storage research!

http://nobelprize.org/nobel_prizes/physics/laureates/2007/press.html

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

Albert Fert
Unite' Mixte de Physique CNRS/THALES, Universit Paris-Sud, Orsay, France,

and

Peter Gruenberg
Forschungszentrum Juelich, 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 Gruenberg 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.

--Andrew J. Klosterman
andrew5 at ece.cmu.edu