title: Irradiation-induced magnetism in graphite: a density functional study.
abstract: Recent experiments indicate that proton irradiation triggers ferromagnetism in originally nonmagnetic graphite samples while He ion bombardment has a much smaller effect. To understand the origin of irradiation-induced magnetism, we have performed spin-polarized density functional theory calculations of the magnetic properties of the defects which are most likely to appear under irradiation vacancies and vacancy-hydrogen complexes. Both defects are magnetic, but as for the latter we find that H adsorption on one of the vacancy dangling bonds gives rise to a magnetic moment double that of the naked vacancy. We show that for small irradiation doses vacancy-hydrogen complexes result in a macroscopic magnetic signal which agrees well with the experimental values.
authors.affiliation: Laboratory of Physics, Helsinki University of Technology, P.O. Box 1100, 02015 Finland.
authors.forename: P O
authors.initials: PO
authors.lastname: Lehtinen
authors.forename: A S
authors.initials: AS
authors.lastname: Foster
authors.forename: Yuchen
authors.initials: Y
authors.lastname: Ma
authors.forename: A V
authors.initials: AV
authors.lastname: Krasheninnikov
authors.forename: R M
authors.initials: RM
authors.lastname: Nieminen