Evidence for Stable High-Temperature Ferromagnetism in Fluorine-Treated C60

Abstract

It is shown by magnetic field dependent ac susceptibility, magnetic force microscopy, and ferromagnetic resonance that exposure of C60 to fluorine at 160°C produces a stable ferromagnetic material with a Curie temperature well above room temperature. The exposure to fluorine is accomplished by decomposing a fluorine-rich polymer, trifluorochloroethylene [F2C–CFCl]n, which has C60 imbedded in it. Based on previous experimental observations and molecular orbital calculations, it is suggested that the ferromagnetism is arising from crystals of C60–F.