Electron spin resonance measurements of proton-irradiated graphite have revealed detailed
nature of proton-irradiation-induced defects. Our results indicate that proton-irradiation
creates confined defect regions of a metallic island surrounded by an insulating magnetic
region which “isolates” the metallic island inside from the metallic graphite background
outside. We have thus come up with a picture of phase separation in proton-irradiated
graphite comprising three regions of distinct electrical and magnetic properties.