MAGNETISM IN C_(60) INDUCED BY POLYMERIZATION

摘要

In the last twenty years there have been many reports on different metal-free organic compounds that exhibit ferromagnetic behavior even at room temperature. The analysis of numerous experimental results shows that they cannot be explained without recognition that ferromagnetic carbon does exist. This evidence supports the theoretical predictions showing that electronic instabilities in pure carbon may give rise to superconducting and ferromagnetic properties even at room temperature. Five types of carbon magnets have been obtained experimentally: (ⅰ) chains of interacting radicals (ⅱ) carbonaceous substances with a mixture of sp~2 and sp~3 coordinated atoms; (ⅲ) amorphous carbon structures containing three-valence elements like P, N, B; (ⅳ) nanographite, nanodiamond, carbon nanofoam; (ⅴ) fullerenes. The diamagnetism of pristine C_(60) is vanishingly small, but the magnetic properties are strongly enhanced in the neutral (undoped) C_(60) polymers, where paramagnetic and even ferromagnetic behavior is observed.