  Electronic, transport, and spin properties of grain boundaries (GBs) are
investigated in electrostatically doped graphene at finite electron densities
within the Hartree and Hubbard approximations. We demonstrate that depending on
the character of the GBs, the states residing on them can have a metallic
character with a zero group velocity or can be fully populated losing the
ability to carry a current. These states show qualitatively different features
in charge accumulation and spin polarization. We also demonstrate that the
semiclassical Thomas-Fermi approach provides a satisfactory approximation to
the calculated self-consistent potential. The conductance of GBs is reduced due
to enhanced backscattering from this potential.
