Monday, February 12, 2007

2007 Japan Prize in technology

This year’s Japan Prize in technology, awarded for breakthrough basic research with a high industrial impact, goes to Albert Fert and Peter Grünberg, who independently described giant magnetoresistance (GMR), in which the electrical resistance of certain materials drops when a magnetic field is applied. GMR enables the high capacity found in today’s hard disk drives.

The Japan Prize is awarded to world-class scientists and technologists credited with original and outstanding achievements and who have contributed to the advancement of science and technology, thereby furthering the cause of peace and the prosperity of mankind.

The Presentation Ceremony will be held in the presence of Their Majesties, the Emperor and Empress in Tokyo in April. The events will also be attended by the Prime Minister, the Speaker of the House of Representatives, the President of House the Councilors, the Chief Justice of the Supreme Court, foreign ambassadors to Japan and about a thousand other guests, including eminent academics, researchers and representatives of political, business and press circles.

The week in which the Japan Prize is presented is designated as "Japan Prize Week." During this period, the laureates give commemorative lectures and attend academic discussion meetings. They take part in various other activities, including a visit to the Prime Minister and The Japan Academy

Every year, the Science and Technology Foundation of Japan (JSTF) selects two categories in which scientists and technologists who are exemplary role models for their behavior are awarded the Japan Prize. For 2007 the two categories are Innovative Devices Inspired by Basic Research and Science and Technology of Harmonious Co- Existence.

In the first category, the motivation is that basic research in science plays an important role as a cornerstone of our modern society. Breakthroughs in physics, chemistry, and other fields of basic research often come to fruition in the form of new materials, or devices, eventually leading to the development of a new industry. The award for 2007 is focused on an accomplishment in developing original findings in basic research into the invention of an innovative device which will likely create a new industry.

Fert and Grünberg’s achievement is the independent discovery of Giant Magneto-Resistance (GMR) and its contribution to development of innovative spin-electronics devices.

In previous magnetic heads used for reading data, magnetoresistance (MR) components had been used. Magnetoresistance is the phenomenon of the change to electrical resistance when subject to a magnetic field. As the electrical resistance change causes the electrical current change, the data written on the hard disk can be read by detecting the electrical current. The resistance change ratio when using the MR component is at most only a few percent.

In contrast to this, when the GMR component is used resistance ratio rises to several tens of percentage. In other words, even a responsibility to a weak magnetic field leads to a vast increase in sensitivity. This means that even when a large amount of magnetic data is stored on a small sized hard disc it is easy to read, and this has resulted in the memory storage capacity of hard discs undergoing great improvements. Thanks to the development of the magnetic head which utilizes GMR effect in the late 1990s, the performance and effectiveness of hard discs is being enhanced at a faster and faster rate.

What is called MR effect—namely the effect of magnetization on the electrical resistance of ferromagnetic materials—has posed a challenge for a long time in both fundamental and applied physics. From the 1970s onward, Fert developed comprehensive, pioneering studies for a quantum mechanical understanding of electrical transport properties in ferromagnetic alloys. Through his research, it became foreseeable in the mid-80's that the effect of spin-dependent scattering would give rise to magneto-resistance effects of unprecedented magnitude, provided one finds a means to switch the relative orientation of the magnetization of successive magnetic layers in a multi-layer from parallel to antiparallel.

In this situation Grünberg, who had a long-standing record of improving the growth and of characterizing the properties of magnetic layers, found that two Fe layers separated by a Cr interlayer couple for a certain Cr thickness antiparallel to each other could be aligned parallel to each other by applying an external magnetic field. Eventually in 1988 he discovered a GMR effect of about 1% at room temperature in such a Fe/Cr/Fe tri-layer system.

Less than a decade after its discovery, the GMR effect was used in magnetic heads in large-capacity small-size hard drives, which are integrated in commercial devices such as personal computers, video recorders, and portable music players. It is quite remarkable that scientific discovery lead to practical applications in such a short period of time.

The new paradigm of spin-electronics pioneered by Fert and Grünberg triggered a great advance in basic research that linked the electrical transport and the magnetic phenomenon, as well as in innovative applied research such as nonvolatile memory (MRAM) making use of the finding. They have opened the way for "innovative devices inspired by basic research."

Compiled from information on the JSTF web site. For more information on MR and GMR, see Janice Nickel, Magnetoresistance Overview, HPL-95-60.