Possible anomalous spin dynamics of the Hubbard model on a honeycomb lattice

In this paper, the Hubbard model on a honeycomb lattice is investigated by using an O(3) nonlinear sigma model. A possible candidate for a quantum non-magnetic insulator in a narrow parameter region is found near the metal-insulator transition. After studying the magnetic properties of the quantum non-magnetic insulator, anomalous spin dynamics is shown. In addition, we find that this region could be widened by hole doping.