Lattice Model for the SU(N) Neel 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 Neel order for J(2)/J(1) >> 1, allowing us access to the transition between these types of states for large N. Using quantum Monte Carlo 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 Neel-valence-bond-solid transition.