Lattice model for the SU(N) néel to valence-bond solid quantum phase transition at large N

We generalize the SU(N=2) S=1/2 square-lattice quantum magnet with nearest-neighbor antiferromagnetic coupling (J ₁) and next-nearest-neighbor ferromagnetic coupling (J ₂) to arbitrary N. For all N>4, the ground state has valence-bond-solid order for J ₂=0 and Néel order for J ₂/J ₁1, allowing us access to the transition between these types of states for large N. Using quantum MonteCarlo simulations, we show that both order parameters vanish at a single quantum-critical point, whose universal exponents for large enough N (here up to N=12) approach the values obtained in a 1/N expansion of the noncompact CPN ^-1 field theory. These results lend strong support to the deconfined quantum-criticality theory of the Néel-valence-bond-solid transition.