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Magnetic Materials : Sato's Group

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Uploaded on Jan 15, 2010

The Sato Laboratory combines both physical and chemical research techniques, with the aim of giving materials new functionality based on physics.

In particular, the Sato Lab studies ways of artificially turning substances that dont stick to magnets into ferromagnetic materials, by considering the basic principles of magnetism. The team is also studying ways of using magnetic materials that are not ferromagnetic. In this way, the researchers are seeking new possibilities for magnetic materials.

Magnetic materials have a wide range of uses, such as hard disks and other memory media, and motors for electric vehicles. Magnetism arises because each atom and electron is a tiny magnet, and when these tiny magnets are aligned, the material is ferromagnetic. Other forms of magnetism include antiferromagnetism, where the atomic magnets are aligned anti-parallel to each other, and spin glasses, where the atomic magnets are aligned randomly.

Despite such a diversity of magnetic materials, so far, most applications have involved improving the performance of ferromagnetic materials, which are well understood. To some extent, the substances that are usable have been limited.

Q. So far, weve wanted to make nonferromagnetic materials into ferromagnetic ones. And weve wanted to utilize materials other than ferromagnetic ones in some way.

Q. To make something ferromagnetic, we have to affect it in some way. First of all, we tried making materials in nano-sized form. In 2003, we found that palladium, which is not ferromagnetic and doesnt stick to a magnet, can be made ferromagnetic by making it nano-sized. Its also possible to make substances exhibit ferromagnetism by applying an electric field. We expect that a variety of new materials can be developed using such methods.

Regarding ways of using materials that are not ferromagnetic, the researchers are focusing on materials called spin glasses. A spin glass is a magnetic material where the spins have frozen in a random arrangement.

The random interaction between spins causes frustration of the spins. In this way, very interesting phenomena have been reported, such as aging, rejuvenation, and memory effects.

Q. This material has a very mysterious memory. Ordinary memory media store 10, but a spin glass has a multi-valued memory; it can store several superimposed data, that is, 12345. Another property is that theres some relation between the memories, so theres some association. For example, a person remembers a blue sky, or a red sunset. If you think of spin arrangement patterns in a magnetic material as memories like that, the patterns are related, so the memories are associated. So were studying spin glasses with the hope that this will lead to new memory media.

Q. In this research, our approach is to use ways of thinking that havent been used before, and to consider things from first principles. If your attitude is to not just transform things that have existed before, but make something new right from the beginning, you can get totally unexpected new results. Making nonferromagnetic materials into ferromagnetic ones, or focusing on spin glasses, which are new materials, is very interesting research. So as we do this research, we hope to make some kind of new discovery.

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