Néel and Spin-Peierls ground states of two-dimensional SU(N) quantum antiferromagnets.

The two-dimensional SU(N) quantum antiferromagnet, a generalization of the quantum Heisenberg model, is investigated by quantum Monte Carlo simulations. The ground state for N<or=4 is found to be of the Néel type with broken SU(N) symmetry, whereas it is of the Spin-Peierls type for N>or=5 with broken lattice translational invariance. Our computation of the magnetization and the dimerization order parameter shows the absence of the intermediate spin-liquid phase.