GRAPHITE, which is normally a good electrical conductor, can be 鈥渟witched
off鈥� and turned into an insulator by placing it in a powerful magnetic
field鈥攁nd now Dmitri Khveshchenko at the University of North Carolina
thinks he knows why.
Graphite conducts electricity because electrons from some of its carbon atoms
are free to roam through the structure, carrying current. In a paper published
in Physical Review Letters, Khveshchenko has calculated that a powerful
magnetic field increases the energy that electrons need to break free from the
carbon atoms, and so prevents current from flowing.
The switching phenomenon could make graphite an important component in future
electronic devices. 鈥淥ne could argue that any controlled metal-to-insulator
transition can be used to build switches, transistors and similar devices,鈥� he
says.
Advertisement