Planar classical dipolar system on a honeycomb lattice

The behavior of a system of dipoles is presented. Here we study a system of dipoles located on a honeycomb lattice under the mean-field approximation with dipoles confined to rotate in the plane of the lattice. It is found that, in zero external field, the system has a ground state which is continuously degenerate, and the degeneracy persists to T{≠}0. For nonzero field pointing in an arbitrary direction in the plane, we compute numerically the magnetization, susceptibility, and the specific heat as functions of both the temperature and the field. Our results show the occurrence of cusps in these quantities, indicating the onset of phase transitions. A phase diagram for the system is constructed on the basis of these calculations.