As part of JST Basic Research Programs, a research group led by Professor Tadahiro Komeda at Institute of Multidisciplinary Research for Advanced Materials, Tohoku University and Professor Masahiro Yamashita at Graduate School of Science, Tohoku University has achieved on-off control of magnets by single molecule using a single-molecule magnet.

 Single spin is a fundamental structural unit of magnetic materials and considered as the smallest magnet.  Magnetic storage media have become smaller as a technology has been developed, and ultimately high-density recording using single spin has gathered attention.  Recently, studies using molecules as a material have often been conducted, which leads to a presentation of single-molecule memory and molecular spinelectronics through a combination of molecular electronics to control electrical current by magnetic control.  A single-molecule magnet that shows magnetic property with only a single molecule is one of the most appropriate molecules as a material for such spin device.  However, it has not been demonstrated that a single molecule controls magnetic property.    

 In this study, using terbium-phthalocyanine complex molecule as a single-molecule magnet, it is shown that on-off control of single-molecule magnet is possible.  The molecule consists of two flat phthalocyanine ligands (Pc) that face each other with one terbium (Tb) metal atom between them (TbPc2).  A technology to apply electrical current to the molecule so that ligands spin around has been developed.  On-off control of single-molecule magnet was achieved by regulating a relative angle between two ligands.    

 The achievement shows a single-spin manipulate technique using molecular structural changes by applying electrical current.  The technique is expected to be applied to single-molecule memory.  Assuming a single molecule has a function as one memory, a single-molecule magnet can provide 6 x 1023 bit-memory, which is 15 trillion times larger capacity than single-sided and-layered DVD discs, and is expected to become ultimately high-density recording.  The research result has been published online in Nature Communications on March 1, 2011.  The paper is entitled “Observation and electric current control of a local spin in a single-molecule magnet.”

More information (Japanese)

[Contact for the research]
Professor Tadahiro Komeda
Institute of Multidisciplinary Research for Advanced Materials, Tohoku University
Address: 2-1-1 Katahira Aoba-ku Sendai, Miyagi, 980-8577, Japan
TEL: +81-22-217-5369、+81-22-217-5368,  FAX: +81-22-217-5371
E-mail: komeda*tagen.tohoku.ac.jp (Replace * with @)

(For JST Programs)
Naoki Nagata
Department of Inclusive Research Administration, Innovation Headquarters, Japan Science and Technology Agency 
Address: Sanban-cho building, 5 Sanban-cho Chiyoda-ku, Tokyo, 102-0075, Japan 
Tel: +81-3-3512-3524, Fax: +81-3-3222-2064 
E-mail: crest*jst.go.jp (Replace * with @)