Wolf Prize Laureate in Physics 2006/7
Affiliation at the time of the award:
Forschungszentrum Juelich, Germany
“for their independent discovery of the giant magnetoresistance phenomenon (GMR), thereby launching a new field of research and applications known as spintronics, which utilizes the spin of the electron to store and transport information”.
The discovery of the giant magnetoresistance (GMR) phenomenon in 1988, by the groups of Professor Albert Fert of the University of Paris, and by Professor Peter Grünberg of the Institut für Festkörperforschung in Jülich, was highly unexpected. Prior to this discovery, it was broadly believed that magnetoresistance – the change in electrical resistance due to an external magnetic field – of ferromagnets could at most reach a few percent. Now, however, the GMR discovered in multilayer ferromagnets can reach levels of 100 percent and more. The effect is based on the arrangement of two successive magnetic layers, separated by a very thin non-magnetic layer. The relative orientation of the magnetization can be easily switched by applying a weak magnetic field, thus affecting the magnitude of the resistance in an unprecedented way. An electric current may flow rather freely if the magnetic layers are oriented parallel, while a high electric resistance results if they are anti-parallel. This discovery has led to major progress in both basic research and applied physics, shifting the focus from the transport of charge (electrical current) to the electron spin. In the resulting new field of spintronics one utilizes the electrons’ spin to transport and to store information.
The field of spintronics encompasses new effects such as: tunnelling magnetoresistance, colossal magnetoresistance, spin injection, spin currents, spins utilized for quantum computation, and the evolution of a new class of materials, magnetic semiconductors.
In the technological arena the GMR has completely revolutionized the magnetic recording industry: the very high sensitivity of GMR-based recording heads has allowed a reduction in the bit size, and hence an enormous increase in the storage capacity and reading speed of magnetic hard-disk drives. Now, some eighteen years after its discovery, all hard-disks in computers are equipped with read heads based on the GMR effect.