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.
|Journal||Physical Review Letters|
|State||Published - Mar 28 2012|
ASJC Scopus subject areas
- Physics and Astronomy (all)