Grünberg, Peter Andreas (1939-2018), a Czech-born German physicist, won a share of the 2007 Nobel Prize in physics for discovering a phenomenon called giant magnetoresistance (GMR). Computer hard drives can use GMR to read data stored on a magnetic disk, converting it into an electrical signal. The discovery of GMR enabled the development of the small, high-capacity hard drives found in many digital music players and laptop computers. Grünberg shared the prize with the French physicist Albert Fert, who discovered GMR independently.
Most materials resist the flow of electric current through them, an effect called electrical resistance. Scientists have long known that the electrical resistance of a magnetic material, such as iron, changes slightly when a magnetic field is applied to the material. A magnetic field is the influence that a magnetic object creates in the region around it. The effect that the field has on resistance, called magnetoresistance, is typically small.
In the 1980’s, Grünberg and Fert found that devices made of thin, alternating layers of magnetic and nonmagnetic metal showed much greater magnetoresistance under certain conditions. This phenomenon became known as “giant” magnetoresistance or GMR. In the 1990’s, GMR proved useful in the design of readout heads that retrieve data stored on hard disks. Such disks store data as small magnetized areas on their surfaces. When a GMR readout head passes over the disk, the magnetic fields from the different areas on the disk change the head’s resistance between low and high, varying the flow of electric current through the head to produce an electrical signal. GMR heads are much more sensitive than traditional readout heads, enabling engineers to design tiny hard disks that hold more data by storing it as smaller magnetized areas.
Grünberg was born on May 18, 1939, in Plzen, Czechoslovakia (now the Czech Republic). He earned a Ph.D. degree in physics in 1969 from Darmstadt University of Technology in Germany. He conducted research at Carleton University in Ottawa, Canada, from 1969 to 1972. Grünberg worked as a research scientist in the Institute of Solid State Research at Jülich Research Center in Germany from 1972 until his death. In 1984, he also became a lecturer at the University of Cologne in Germany. Grünberg was appointed an adjunct professor of physics there in 1992, a position he held until he retired in 2004. Grünberg died on April 7, 2018.
