Laser controlled magnetism in hydrogenated fullerene films

• Room temperature ferromagnetic-like behavior in fullerene photopolymerized films treated with monatomic hydrogen is reported. The hydrogen treatment controllably varies the paramagnetic spin concentration and laser induced polymerization transforms the paramagnetic phase to a ferromagnetic-like one. Excess laser irradiation destroys magnetic ordering, presumably due to structural changes, which was continuously monitored by Raman spectroscopy. We suggest an interpretation of the data based on first-principles density-functional spin-unrestricted calculations which show that the excess spin from mono-atomic hydrogen is delocalized within the host fullerene and the laser-induced polymerization promotes spin exchange interaction and spin alignment in the polymerized phase.

Nyckelord

ab initio calculations

density functional theory

exchange interactions (electron)

ferromagnetic materials

ferromagnetic-paramagnetic transitions

fullerenes

hydrogen

laser beam effects

magnetic thin films

paramagnetic materials

polymerisation

Raman spectra

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