Spontaneous quantum Hall effect in quarter-doped Hubbard model on honeycomb lattice and its possible realization in quarter-doped graphene system · arXivDesk
1103.2420Mar 12, 2011A proof of the exact equivalence between the quarter-doped Hubbard model on honeycomb lattice and the 3/4-filled Hubbard model on triangular lattice in the weak coupling limit is added
Spontaneous quantum Hall effect in quarter-doped Hubbard model on honeycomb lattice and its possible realization in quarter-doped graphene system
We show that as the result of the nesting property of the Fermi surface, the quarter-doped Hubbard model on honeycomb lattice is unstable with respect to the formation of a magnetic insulating state with nonzero spin chirality for infinitesimally small strength of electron correlation. The insulating state is found to be topological nontrivial and to have a quantized Hall conductance of σxy=he2
Nearby in the stack
. We find the Fermi surface nesting is robust for arbitrary value of next-nearest-neighbor hopping integral. It is thus very possible that the quarter-doped graphene system will realize such an exotic ground state. We also show that the quarter-doped Hubbard model on honeycomb lattice is in exact equivalence in the weak coupling limit with the 3/4-filled Hubbard model on triangular lattice, in which similar effect is also observed.