The Magnetic Order in Ion Irradiated Graphite

The magnetism of highly oriented pyrolytic graphite (HOPG) induced by ion implantation is investigated with electron spin resonance (ESR) spectroscopy and magnetization measurements. The results indicate that the ESR spectra of the HOPG sample correlate with ion species, incident energy and dose of implantation. The correlation of the ESR spectra and magnetism of the HOPG sample with ^12C^+ ion implantation and H^+ ion implantation are studied in detail. The ferromagnetism of the HOPG sample is likely related to the asymmetric L1 line, which may be attributed to the interaction between localized defects and itinerant electrons occupied in the 'impurity' band induced by ion implantation.