Symmetry of magnetic excitons in two-dimensional Mott insulators

Abstract Symmetry of photoexcited states with two photoinduced carriers in two-dimensional Mott insulators is examined by applying the numerically exact diagonalization method to finite-size clusters of a half-filled Hubbard model in the strong-coupling limit. By applying an averaging procedure for twisted boundary conditions for a 4 × 4 cluster, we find that the symmetry of the lowest-energy bound state, i.e., magnetic exciton, is s-wave. This is consistent with larger clusters of 18, 20, and 26 sites.