MAGNETIC THIN-FILMS OF COBALT NANOCRYSTALS ENCAPSULATED IN GRAPHITE-LIKE CARBON

A VARIETY of crystalline materials have now been encapsulated in nanom etre-scale graphitic cages(1-8) and tubules(9-11). For magnetic materi als, encapsulation should serve the dual role of protecting air-sensit ive particles against degradation and reducing the magnetic coupling b etween individual particles, thus potentially opening the way for appl ications of these composite materials as ultra-high density magnetic r ecording media(12-13). But to realize this potential, the materials mu st be available in the form of thin, smooth films, with precise contro l of the size of the individual magnetic crystallites. Here we report the fabrication and characterization of magnetic thin films, consistin g of cobalt nanocrystals encapsulated in graphite-like carbon cages, t hat meet these structural requirements.