Carbon Magnets Get Hot
A team of researchers has created the first purely organic magnet that works above room temperature. The new magnet, described in the 18 October issue of Nature, is made from spherical carbon molecules called fullerenes or buckyballs. If the feat can be repeated with cheaper organics such as plastics--a big if--it could pave the way for lightweight flexible magnets that could revolutionize everything from computer data storage to what we use to pin photos to our refrigerators.
Though magnets have been made from iron-based minerals such as lodestone and ferrites for centuries, organics have only recently been put to work. In 1991, Japanese researchers found that a nitrogen- and oxygen-containing organic acted as a powerful magnet, with a major drawback: It did so only at temperatures just above absolute zero. A more practical carbon magnet, researchers hope, might open the door to other organic magnets, like those made of plastic--a cheaper, more flexible, and lighter alternative to iron magnets.
Tatiana Makarova, a physicist at the Ioffe Physico-Technical Institute in St. Petersburg, Russia, who is spending a year in Sweden at Umea University, crafted the organic magnet by chance. Two years ago she was trying to design a superconductor with a polymerized form of C60, created by fusing neighboring C60 molecules in a high-pressure device. Though the superconductor didn't materialize, Makarova and colleagues from Russia, Germany, and Brazil found that the C60 polymer was magnetic up to oven temperature, 230°C, and stable in air. "We didn't believe it, and thought there must have been some impurities," Makarova says. But tests on multiple purified samples since then have erased her doubts.
"If true, it's an exciting result," says Joel Miller, an organic magnet expert at the University of Utah in Salt Lake City. Miller says he still wonders whether impurities are skewing the results, a question that should be answered as other teams try to repeat the experiment. C60 magnets aren't likely to have much practical value because the fullerene is expensive and only tiny amounts can be polymerized at a time.