Light-activated plastic magnet

Photo-induced magnetism is of considerable interest—for example, in data storage applications. Over the past six years, the phenomenon has been seen, generated, and studied in several different materials. Now, scientists at Ohio State University and the University of Utah have produced light-induced magnetization in an organic-based material, Mn(tetracyanoethylene) _x · y(CH₂Cl₂) (x ≈ 2; y ∼ 0.8). When the material was exposed to blue light from an argon laser, its magnetization increased by as much as 50%. The material was magnetic at temperatures below 75 K and retained its magnetism for days, perhaps through the formation of a metastable state in a distorted lattice. The magnetism could be partially undone by green light, and completely undone by heat. The researchers believe that the light can be selectively targeted to domains as small as, or smaller than, the wavelength of the light itself, thus possibly enabling information storage. Magneto-optic effects are currently used only to retrieve information. The new process promises to offer both reading and writing capabilities. The benefits of plastic electronic components made of plastic include flexibility, low cost, and tunability. (D. A. Pejakovićet al., Phys. Rev. Lett., 88 , 057202, 2002 http://dx.doi.org/10.1103/PhysRevLett.88.057202 .)