  Twisted graphene bilayers (TGBs) have low-energy van Hove singularities
(VHSs) that are strongly localized around AA-stacked regions of the moire
pattern. Therefore, they exhibit novel many-body electronic states, such as
Mott-like insulator and unconventional superconductivity. Unfortunately, these
strongly correlated states were only observed in magic angle TGBs with the
twist angle theta~1.1{\deg}, requiring a precisely tuned structure. Is it
possible to realize exotic quantum phases in the TGBs not limited at the magic
angle? Here we studied electronic properties of a TGB with theta~1.64{\deg} and
demonstrated that a VHS splits into two spin-polarized states flanking the
Fermi energy when the VHS is close to the Fermi level. Such a result indicates
that localized magnetic moments emerge in the AA-stacked regions of the TGB.
Since the low-energy VHSs are quite easy to be reached in slightly TGBs, our
result therefore provides a facile direction to realize novel quantum phases in
graphene system.
