2001-10-18 09:36:07 -- The World's No.1 Science & Technology News Service
Non-metallic magnet could be dream computer memory
19:00 17 October 01
A transparent, flexible magnetic material made from an exotic form of carbon could turn out to be the dream computer memory. The substance, which was discovered accidentally by a Russian physicist hunting for high-temperature superconductors, is the first non-metallic magnet to work at room temperature.
Tatiana Makarova, working at Umeå University in Sweden, discovered the material while experimenting with buckyballs, football-shaped molecules made up of 60 carbon atoms. By heating and compressing the molecules, she forced them to join together in layers like sheets of bubble wrap, because she thought these might be able to superconduct.
But to her surprise, she found instead that the new material was magnetic even above 200 °C. Until now, the highest temperature at which a non-metallic material was magnetic was 255 °C. This record was held by a different form of buckyballs.
Organic magnets could be important because they are much lighter than their metallic cousins. Also, Makarova's material is flexible and transparent, properties that could make it useful for storing data when a laser is used to record on it. It might also be possible to record data at unprecedented densities.
Exactly why the material is magnetic is not yet clear. Makarova believes that unpaired electrons may play a crucial role, since they can sustain a magnetic field when their spins are aligned. One possibility is that the magnetism stems from buckyballs bonding in triangular groups of three.
"In this configuration, there can be unpaired spins," she says. Her team is currently comparing buckyball layers made in different ways to try to find out.
Robert Blinc, an expert on molecular magnets at the University of Ljubljana in Slovenia, says the work is a giant step forward. He says it is not yet clear whether the magnetic properties are uniform throughout the structure or occur in clumps. "But in any case it is extremely important," he says.