The most common method to change magnetization in materials by electricity is using electromagnet with coil, and this method is applied in many scenes. However, a formation of coil is not suitable for integrated devices, and researches on alternatives to electromagnet are often conducted. For instance, magnetization in magnetic random-access memory (MRAM), one of candidates for the next-generation nonvolatile memory, is controlled by applying electrical current from nearby ferromagnet. This method needs to pass a high current, and ingenerates massive amount of heat, which causes two problems of increased temperature of elements and energy consumption. A method to electrically change magnetization in insulators that allow almost no current to pass has been found 50 years ago. Although it is possible to decrease power consumption significantly in insulators, they are not suitable to be applied because magnetization change in existing insulators by an electric field is too small.

Institute of Multidisciplinary Research for Advanced Materials, Tohoku University has found that magnetization direction in a material that has magnetization and allows no current to pass rotates ±30 degrees by an electric field. The research group verified that the magnetization direction can change in less than 1/10000 second by an applied electric field, and that the same results are available after the direction changes 10 million times. It is the first time in the world that such a fast and repeatable control of magnetization direction by electricity is reported.

In this study, the research group has used (Cu,Ni)B2O4 with a nominal Ni concentration of 5% in copper metaborate, a composite compound of copper and metaboric acid. By cooling this material to have a spontaneous magnetization, and applying an electric field, magnetization direction rotates by large degrees. The material can be an electric magnet without coil because magnetization changes by attaching electrodes to both sides of a magnet and applying an electric voltage. This is applicable to a micrometer-size electromagnet without coil. It is noteworthy that the material allows no current to pass, and energy loss caused by carrying electric current can be prevented.

This research has been conducted by Professor Takahisa Arima at Institute of Multidisciplinary Research for Advanced Materials and Mr. Saito, a student at Graduate School, Tohoku University, and results have been published in “Nature Materials” (an academic journal in U.K.) on June 28, 2009.

[Contact]
Professor Takahisa Arima
Institute of Multidisciplinary Research for Advanced Materials, Tohoku University
Tel: +81 22-217-5348 Fax: +81 22-217-5404
E-mail: arima@tagen.tohoku.ac.jp