  We investigate the resonant two-magnon Raman scattering in the
two-dimensional (2D) and ladder-type Mott insulators by using a half-filled
Hubbard model in the strong coupling limit. By performing numerical
diagonalization calculations for small clusters, we find that the model can
reproduce the experimental features in the 2D that the Raman intensity is
enhanced when the incoming photon energy is not near the absorption edge but
well above it. In the ladder-type Mott insulators, the Raman intensity is found
to resonate with absorption spectrum in contrast to the 2D system. The
difference between 2D and the ladder systems is explained by taking into
account the fact that the ground state in 2D is a spin-ordered state while that
in ladder is a spin-gapped one.
