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[Keio Spintronics Network - Otani Laboratory The University of Tokyo] Institute for Solid State Physics The Ohtani Laboratory at Institute for Solid State Physics of Tokyo the University of Tokyo,s Institute for Solid State Physics is doing R&Dresearch on spintronics, which is expected to be a key technology for next-generation integrated circuits. The electronics technology utilized in integrated circuits so far uses only the charge degree of freedom possessed by electrons. But spintronics technology can also use the spin degree of freedom, which makes electrons act like magnets. This has enabled the development of devices with even higher performance. Q. First of all, we I did experiments with permanent magnets when I was a Ph D course student, to see how small they could be made. When we wereI was researching studying topics such as why permanent magnets are stable, we arrived at a micro-magnetic structure like this. When this is made small, the directions of magnetization can beare aligned. And we thought it was very interesting that, when we pass a current through it, we can extract spins. Right now, were thinking about what other things can be done using this micro-magnetic structure. Among various aspects of spintronics, the Ohtani Lab is focusing on spin-polarized current. The spins flowing in a material are of two types, called up and down. Because there are normally equal numbers of each type, their magnetism is cancelled out. But in ferromagnetic materials, the current flowing can have different proportions of up and down spins. Such a current is called a spin-polarized current. Currently, most laptop hard disks use this principle for reading data. But because the magnetically recorded data is converted to electrical signals for processing, the Ohtani Lab is researching how to manipulate and process data while its still in the form of spin. As a technology for achieving this, the researchers are looking at pure spin current, where only spin flows, without a flow of charge. Q. What we want are control methods like rewriting: ways to effectively inject spins from ferromagnetic materials, get a pure spin current on the right side alone, convert an electric current to a spin current, use reconversion for reading data, and reverse the direction of magnetization using a pure spin current. Theres a question mark over this, but right now, were looking at one difficult issue: that is, pure spin currents decay and attenuate rapidly, so we want a way to amplify them. This is one of the research themes were working on. If R&Dresearch on spin-polarized current and pure spin current progresses, this will be a big step towards spintronics devices, which function with high performance and no energy loss. In this way, spintronics technology will support the information-intensive society of the future. Professor Yoshichika Ohtani talks about why this research is so interesting. Q. Research where the goal is decided from the start isnt really interesting; its as if everything youre doing has already been understood. But if youre trying to make a quantum computer or something like that, you dont know what will happen. People do that kind of research because it has unknown aspects. What is spin? And how far can the relaxation of spin polarization be controlled? Various discoveries can be made by looking at fundamental things. And were interested in how far they can be used to control physical properties.