Carbon Foam Reveals a Fleeting Magnetic Personality

摘要

Hold a magnet up to a piece of graphite or a diamond and not much happens. But researchers from Greece and Australia reported here last week that they've created a spongy, ultralightweight form of carbon that for a few brief hours is strongly magnetic. If they can make the magnetism stick around, the material could prove useful in everything from medical imaging and cancer therapy to exotic electronic circuitry based on the magnetic behavior of electrons rather than their charge. "It's a very intriguing material," says Mildred Dresselhaus, a physicist at the Massachusetts Institute of Technology in Cambridge. David Tomanek, a physicist at Michigan State University in East Lansing who collaborated with the Greek and Australian team on the magnetic theory of the nanofoam, adds that the work underscores how nanotechnology can change long-held understandings of which materials can be magnetic. "It shows that we need to revisit the magnetic prejudice of the periodic table," Tomanek says.