French physicist Albert Fert shared the 2007 Nobel Prize in Physics – along with several other awards including the Wolf Prize and Japan Prize – with Peter Grünberg for their independent but almost simultaneous discovery of Giant Magnetoresistance (GMR). The phenomenon uses quantum physics for boosting the efficiency of hard drives and their readers, allowing drastic reduction – in both size and price – of computers and other digital technology down to that most ubiquitous of modern luxuries, the iPod. Hard disks store information in minute magnetic parcels which are then read and decoded into text, images or sound. To get a smaller disk naturally involved either reducing the information capacity or compressing the parcels, resulting in a weaker signal.
In 1988 Fert discovered a new physical effect – Giant Magnetoresistance (GMR), simultaneously and independently discovered by German Peter Grünberg. The effect is based on the quantum-mechanical combination of electron spins in sandwiched nano layers of the read out head – the electrical resistance of thin magnetic layers can be greatly changed through external magnetic fields, effectively amplifying the signal to make it easier to read. Through a deal with IBM the first read-out head based on the GMR effect was launched in 1997 and this is still the basis of modern read-out techniques of today. Although Grünberg filed the patent for GMR, it was Fert who first coined the name.
Fert was born in Carcassonne, France, in 1938. He studied mathematics and physics at the École Normale Supérieure from 1957, graduating in 1962 to the Université de Paris where he gained his masters degree the following year for a thesis on nuclear magnetic resonance (NMR). He followed this with his PhD in 1970 at the Université Paris-Sud for his work on the transport properties of nickel and iron. Fert worked throughout his studies – as an assistant at the Université de Grenoble from 1962–4, followed by a year spent in national military service, during which time he also joined the Université Paris-Sud as a senior assistant until 1976 when he was promoted to professor of physics. He has remained there ever since. From 1970–95 Fert led a research group at Paris-Sud’s Laboratoire de Physique des Solides and it was there that he performed his Nobel-winning work, with his team working in collaboration with Thales (then Thomson-CSF). Since the discovery of GMR, Fert and his team have continued to explore the use of electron spin on electrical conduction, and in 1995 Fert was made director of the combined CNRS/Thales Joint Physics Unit, developing the new science of ‘spintronics’.
Fert is married to Marie José Fert and they have two children.
This text and the picture of the Nobel Laureate were taken from the book: "NOBELS. Nobel Laureates photographed by Peter Badge" (WILEY-VCH, 2008).
By Volker Steger
When I write this, I hear the quiet hum of the hard disc in my
computer. Which is partly Albert Fertʼs fault. His discovery lies at the
heart of the technology. It is fascinating to see how
this dicovery can be reduced to a simple graph.
After all, it has created entire industries!
Während ich dies schreibe, höre ich das leise Brummen der
Festplatte in meinem Computer - was zum Teil auch
Albert Ferts Schuld ist. Seine Entdeckung liegt dieser
Technologie zugrunde. Es ist faszinierend zu sehen,
wie man die Entdeckung mit einem einfachen
Diagramm erklären kann. Schließlich ist sie die
Basis einer ganzen Industrie.
The Birth of Spintronics
by Adam Smith
The red, blue and black curves you see on the right of Albert Fert’s sketch recreate the experimental record of his discovery, made in 1988, of a phenomenon he called Giant Magnetoresistance, or GMR for short. As the applied magnetic field (H) changed, he saw dramatic variations in the electrical resistance (R) of the specially constructed, layered metal stacks he was studying. The same unexpected finding was observed, quite independently, by Fert’s co-Laureate, Peter Grünberg, the very same year. Their discoveries quickly found applications in our daily lives, for instance by vastly increasing information storage capacity. Indeed, if you’re reading this on screen, then you might enjoy the thought that GMR lies at the heart of the device you’re reading it on.
The fact that magnetic fields can influence the electrical properties of metals had been known since 1856, when ‘magnetoresistance’ was first observed, and named, by William Thomson. But the magnitude of the effects recorded by Fert and Grünberg was astonishingly big; hence ‘Giant’ magnetoresistance. The conductors they studied were examples of ‘nanostructures’, made from extremely thin, alternating layers of materials, deposited in bands just a few atoms thick.
On the left of his sketch, Fert has attempted to explain the phenomenon, which has its origins in the quantum mechanical property of electron spin. The black arrows represent the direction of the applied magnetic field, and the red and blue arrows the direction of the individual electron spins. When the magnetic field is used to align the electrons in successive magnetic layers, as in the bottom diagram, current passes easily. But when the applied magnetic field causes the electrons to adopt opposite spins, current flow is blocked. A useful analogy is to think of polarising filters in sunglasses, which only allow light to pass through when the alignment of the light waves matches that of the polariser, whereas crossed polarisers block the passage of light completely.
One consequence of Fert’s discovery of GMR was the growth of an entirely new field of research called spintronics, which, in contrast to conventional electronics, makes use of not just the charge but also the spin of the electron. “This discovery was 30 years ago,” remarks Fert. “A long time ago, but today I am still presenting new results, results in a new direction of this field of research called spintronics. In fact this is what is amazing; science is always developing.”