French scientist Albert Fert and Peter Grunberg of Germany have won the 2007 Nobel Prize in physics after discovering the phenomenon of "giant magnetoresistance" (GMR), in which weak magnetic changes give rise to big differences in electrical resistance. The knowledge has allowed the development of sensitive reading tools to pull data off hard drives in computers and portable digital devices. GMR, which involves structures consisting of very thin layers of different magnetic materials, has made it possible to radically miniaturise hard disks in recent years.
For this reason it can also be considered "one of the first real applications of the promising field of nanotechnology. Applications of this phenomenon have revolutionised techniques for retrieving data from hard disks. The discovery also plays a major role in various magnetic sensors as well as for the development of a new generation of electronics," according to the Royal Swedish Academy of Sciences. A hard disk stores data in the form of microscopic areas that are 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 needed when more information is crammed on to a hard disk.