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 Umeе 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.