The research group consisted of Professor Maekawa (Institute for Materials Research, Tohoku University), Professor Tanaka (Department of Electrical Engineering and Information Systems, The University of Tokyo), and Professor S.E. Barnes (Physics Department, University of Miami) found that an electromotive force (e.m.f) can indeed be induced by a static magnetic field in magnetic tunnel junctions containing zinc blende-structured MnAs quantum nanomagnets. The observed e.m.f results from the conversion of the magnetic energy of the super-paramagnetic MnAs nanomagnets into electrical energy when these magnets undergo magnetic quantum tunneling. As a consequence, a huge manetoresistance of up to 100,000 per cent is observed for certain bias voltage. Their results strongly supported the contention that, in magnetic nanostructures, Faraday's law of induction must be generalized to account for forces of purely spin origin. The huge magnetoresistance and e.m.f. may find potential applications in high sensitivity magnetic sensors, as well as in new active devices such as 'spin batteries'. This research achievement was published in British Science Journal "Nature" on online version on 8 March, 2009.

Contact:

Professor Maekawa Sadamichi
Institute for Materials Research Tohoku University
Phone: +81-22-215-2005  FAX: +81-22-215-2006
EMAIL: maekwa__AT_imr.tohoku.ac.jp (Replace _AT_ to @)

Assistant Professor Ieda Junichi
Institute for Materials Research Tohoku University
TEL: +81-22-215-2009  FAX: +81-22-215-2006
EMAIL: ieda_AT_imr.tohoku.ac.jp (Replace _AT_ to @)