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Peter Grünberg Awarded Nobel Prize in Physics 2007


The Nobel Committee jointly awarded the Nobel Prize in Physics 2007 to the PGI-6 researcher Peter Grünberg and his colleague Albert Fert from the University of Paris-Sud. The physicists were honoured for their discovery of the giant magnetoresistance (GMR) effect.

The GMR effect led to a breakthrough in gigabyte hard disks and laid the foundation for the field of spintronics. In particular, after the implementation of the GMR effect in read heads in 1997, less than ten years after the discovery, the annual increase in the storage density of hard discs rose from 60 percent to almost 100 percent.

Giant Magnetoresistance (GMR)

Effects such as the giant magnetoresistance effect (GMR) occur only in artificial multilayer structures, for example, in two magnetic layers of iron that communicate (couple) with each other via an intermediate film. For the GMR effect to occur, the mid-layer must consist of a non-ferromagnetic, electrically conducting material such as chromium. This layer must only be a maximum of a few nanometres in thickness and its interfaces must be of the very best quality. This type of "sandwich" structure changes its resistance by more than 50 percent while exposed to an external magnetic field. GMR stacks are found in highly sensitive magnetic field sensors, and are used for example in read heads of computer hard disks.

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