Page 215 - Science at the nanoscale

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June 5, 2009
9.3. Spintronics and Surface Chemistry
(GMR)”. GMR is a quantum mechanical effect observed in
thin film structures composed of alternating ferromagnetic and
nonmagnetic metal layers. The effect manifests itself as a signif-
icant decrease in electrical resistance in the presence of a mag-
netic field. The Nobel Foundation’s press release interestingly
6
concludes with this paragraph :
“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 was made in 1988, and it was realised that this
effect would make it possible to manufacture very sensitive mag-
netic read heads for hard disks.
In a remarkably short time,
GMR technology was incorporated into their hard drive head
and launched onto the market by IBM in 1997. This invention
is responsible for the ultra-high density disk drives in MP3 play-
ers, digital video recorders, and computer notebooks (see Fig. 9.2).
7
The IBM GMR website proudly reads: “The Giant Magnetoresistive
Figure 9.2. Left: A hard disk drive; Right: Close-up of a disk drive 205 ch09
head resting on the reflective disk platter together with its mirror image
[Left image: Source – http://commons.wikimedia.org/w/index.php?
title=Image:Hard disk.jpg&oldid=11516558, Right image: Image cour-
tesy of Mr. Andrew Magill. Copyright c
2006 by Andrew Magill
www.ominoushum.com]
6 http://nobelprize.org/nobel prizes/physics/laureates/2007/press.html
7 http://www.research.ibm.com/research/gmr.html