Peter Grünberg
German physicist whose work paved the way for smartphones
PETER GRÜNBERG, who has died aged 78, was a German solid state physicist who shared the 2007 Nobel Prize in Physics with the French scientist Albert Fert for their development of a novel technology used to read data on hard disks, allowing them to be miniaturised, thus paving the way for gadgets such as the MP3 player, the smartphone and ipod.
In 1988 both men, working separately, discovered a hitherto unknown magnetic effect known as giant magnetoresistance (GMR), whereby a small magnetic field can induce a large change in the electrical conductivity of a material composed of sandwiched nanolayers (ie, only a few millionths of a millimetre thick) of magnetic and non-magnetic materials. The magnetic layers behave a little like bar magnets pointing in one of two directions, north or south.
When a current is induced into this sandwich, electrons move through the layers. However, the degree of hindrance they experience is different depending upon an intrinsic quantum characteristic of electrons that scientists call “spin” (even though the electrons are not actually spinning). Instead, “spin” means each electron acts like a miniature magnet pointing either up or down.
In the magnetic layers this spin can be aligned to or counter to the direction of the bar magnet. The upshot is that electrons with a spin in one direction will move more freely and hence be the predominant carriers of the current through the layer, so the flow of electrons through the sandwich can be controlled by the relative arrangement of the bar magnets of the top and bottom layers.
The discovery paved the way to storing individual bits of data as magnetic domains on a spinning disk, with the changes in conductivity they induce in a reading head held over the disk capable of being turned into signals that a computer can process. The result has been that the amount of data computers can store has grown even faster than their ability to process it.
The first disk-reading device based on the effect was launched in 1997 and is now the standard technology behind a consumer goods market worth billions. The Nobel Prize Committee observed that GMR “can also be considered one of the first real applications of the promising field of nanotechnology”.
Peter Andreas Grünberg was born on May 18 1939 to a Sudeten German family in Pilsen, Bohemia, two months after the area had been occupied by Germany, becoming an autonomous Nazi-administered territory as the Protectorate of Bohemia and Moravia (now the Czech Republic). His father was an engineer who worked for the Skoda factory in Pilsen designing locomotives.
The family was interned by the Czechoslovak authorities after the war. Peter’s father died in prison towards the end of 1945 and was buried in a mass grave. The rest of the family, including seven-year-old Peter, was expelled from Czechoslovakia in 1946 and settled at Lauterbach, Hesse.
He went on to study at the Johann Wolfgang Goethe University in Frankfurt and the Darmstadt University of Technology, where he took a degree in Physics followed by a PHD. From 1969 to 1972 he did postdoctoral work at Carleton University in Ottawa, Canada. He later joined the Institute for Solid State Physics in the western German town of Jülich, where he remained until his retirement in 2004.
Apart from the Nobel Prize, Grünberg’s work was recognised with several more prizes, including the Wolf Prize in Physics, the 2006 European Inventor of the Year award of the European Commission, and the 2007 Japan Prize.
In 1966 he married Helma Prausa, with whom he had two daughters and a son.
Peter Grünberg, born May 18 1939, died April 7 2018