  The electronic properties of van der Waals (vdW) structures can be
substantially modified by the moire superlattice potential, which strongly
depends on the twist angle among the compounds. In twisted bilayer graphene
(TBG), two low-energy Van Hove singularities (VHSs) move closer with decreasing
twist angles and finally become highly non-dispersive flat bands at the magic
angle (~ 1.1 degree). When the Fermi level lies within the flat bands of the
TBG near the magic angle, Coulomb interaction is supposed to exceed the kinetic
energy of the electrons, which can drive the system into various strongly
correlated phases. Moreover, the strongly correlated states of flat bands are
also realized in other graphene-based vdW structures with an interlayer twist.
In this article, we mainly review the recent experimental advances on the
strongly correlated physics of the magic-angle TBG (MATBG) and the small-angle
twisted multilayer graphene. Lastly we will give out a perspective of this
field.
