Electrical Switching between Paramagnetic and Ferromagnetic States ("Chameleon" Magnets) in Cobalt-Doped Titanium Dioxide

Researchers from Japan Science and Technology Agency (JST) and the University of Tokyo and Tohoku University suggested a possibility to control a magnet's behaviour

*Note: This news was first mentioned in the June 2011 issue of Nanotech Japan Update*

Japan Science and Technology Agency (JST), the University of Tokyo and Tohoku University announced on 27th May 2011 that a research team from both Universities led by Associate Professor T. Fukumura of the University of Tokyo has succeeded in observing paramagnetic-ferromagnetic transition induced by electric field-effect ("chameleon" magnets) in transparent oxide semiconductor TiO2 doped with cobalt, (Ti, Co)O2 and that the details of the results are published in the scientific Journal Science on the same day.

Fukumura et al. observed electric field-induced ferromagnetism at room temperature in (Ti0.9Co0.1)O2 with electric double-layer gating FET-structure, which enabled a high-density electron accumulation of >1014/cm2. By applying gate voltages of a few volts, a low-carrier paramagnetic state was transformed into a high-carrier ferromagnetic state, suggesting a possibility to room-temperature spintronics. This research was supported by JST as a PRESTO Project.

On this paper, Professor Igor Zutic of the State University of New York at Buffalo contributed a perspective comment in the same issue of Science.

Published: 28 Jun 2011

Contact details:

STAM editorial office

National Institute for Materials Science (NIMS) 1-2-1 Sengen, Tsukuba-city Ibaraki 305-0047 JAPAN

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http://nanonet.mext.go.jp/english/modules/news/article.php?a_id=751 News Article on NanoTech Japan
http://www.jst.go.jp/pr/announce/20110527/index.html News Release from Japan Science and Technology Agency (Japanese)
http://www.buffalo.edu/news/12608 News Release from the University of Buffalo


A. Yamada, K. Ueno, T. Fukumura, H. T. Yuan, H. Shimotani, Y. Iwasa, L. Gu, S. Tsukimoto, Y. Iku-hara, and M. Kawasaki, "Electrically Induced Ferromagnetism at Room Temperature in Cobalt-Doped Titanium Dioxide", Science Vol. 332, No. 6033, pp. 1065-1067 (2011)-DOI: 10.1126/science.10120215.

Igor Zutic and John Cerne, "Chameleon Magnets," Science Vol. 332, No. 6033, pp. 1040-1041 (2011) DOI: 10.1126/science.1205775