62 nanotimes News in Brief

A RIKEN-led research team in Japan has now demonstrated the origin of magnetism in organic molecules. The permanent magnetic properties of materials such as iron stem from an intrinsic mechanism called ferromagnetism. Ferromagnetism in organic materials is rare because their atomic structure is fundamentally different from metals. One of the few examples identified to date is called TDAE-C60 (see fig.): a compound comprising spherical carbon cages attached to an organic molecule known as tetrakis-dimethylamino-ethylene. Since its identification in 1991, many theoretical and experimental studies have provided some insight into the mechanism driving this unexpected ferromagnetism, but the explanation was not definitive. A full understanding would help materials scientists to develop more advanced magnetic materials in the future. 

"A precise model for organic magnetism could aid the design of high-density recording materials for use in next-generation memories," says team member Hitoshi Yamaoka from the RIKEN SPring-8 Center, Harima, Japan. "From these experiments on a single crystal we could establish an exact theoretical model for organic magnetism," explains Yamaoka. "We propose that the transfer of one electron from the TDAE to the C60 causes the magnetic properties of TDAE-C60."

Hitoshi Yamaoka, Takashi Kambe, Tohru Sato, Yukiaki Ishida, Masaharu Matsunami, Ritsuko Eguchi, Yasunori Senba, and Haruhiko Ohashi: Electronic state of an organic molecular magnet: Soft x-ray spectroscopy study of α-TDAE-C60 single crystal, In: Physical Review B, Volume 84, Issue 16, Article 161404(R) [4 pages], DOI:10.1103/PhysRevB.84.161404: 

_{http://dx.doi.org/10.1103/PhysRevB.84.161404}