  We demonstrate direct evidence for ferromagnetic order at defect structures
in highly oriented pyrolytic graphite with magnetic force microscopy at room
temperature. Magnetic impurities have been excluded as the origin of the
magnetic signal after careful analysis supporting an intrinsic magnetic
behavior of carbon-based materials. The observed ferromagnetism has been
attributed to originate from unpaired electron spins localized at grain
boundaries. Scanning tunneling spectroscopy of grain boundaries showed intense
localized states and enhanced charge density compared to bare graphite.
