  Orbital angular momentum (OAM) of graphene electrons in a perpendicular
magnetic field is calculated and corresponding magnetic moment is used to
investigate the magnetism of perfect graphene. Variation in magnetization
demonstrates its decrease with carrier-doping, plateaus in a large field, and
de Haas-van Alphen oscillation. Regulation of magnetism by a parallel electric
field is presented. The OAM originates from atomic-scale electronic motion in
graphene lattice, and vector hopping interaction between carbon atomic orbitals
is the building element. A comparison between OAM of graphene electrons, OAM of
Dirac fermions, and total angular momentum of the latter demonstrates their
different roles in magnetism of graphene. Applicability and relation to
experiments of the results are discussed.
