Carbon's mysterious magnetism

11:09am, May 25, 2007

An X-ray experiment has produced the most conclusive evidence yet that carbon can be made into a permanent magnet.

Only a few elements are magnetic at room temperature. They are metals whose atoms have a magnetic moment arising from the spin of an unpaired electron. Pairs of electrons with opposite spin produce no net magnetic moment. Since carbon tends to form covalent bonds, which contain paired electrons, it seems an unlikely candidate to be magnetized.

But several experiments have suggested that under certain conditions, forms of bulk carbon such as graphite can acquire a feeble permanent magnetization. Most physicists regard these results with skepticism, however, since even trace contamination by a metal such as iron could make a sample slightly magnetic.

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