title: Lattice model for the SU(N) Néel to valence-bond solid quantum phase transition at large N.
abstract: 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(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 CP(N-1) field theory. These results lend strong support to the deconfined quantum-criticality theory of the Néel-valence-bond-solid transition.
authors.affiliation: Department of Physics & Astronomy, University of Kentucky, Lexington, Kentucky 40506-0055, USA.
authors.forename: Ribhu K
authors.initials: RK
authors.lastname: Kaul
authors.forename: Anders W
authors.initials: AW
authors.lastname: Sandvik