Consistent Scaling Exponents at the Deconfined Quantum-Critical Point

We report a quantum Monte Carlo study of the phase transition between antiferromagnetic and valence-bond solid ground states in the square-lattice S=1/2 J–Q model. The critical correlation function of the Q terms gives a scaling dimension corresponding to the value \nu = 0.455 \pm 0.002 of the correlation-length exponent. This value agrees with previous (less precise) results from conventional methods, e.g., finite-size scaling of the near-critical order parameters. We also study the Q-derivatives of the Binder cumulants of the order parameters for L^2 lattices with L up to 448. The slope grows as L^1/\nu with a value of \nu consistent with the scaling dimension of the Q term. There are no indications of runaway flow to a first-order phase transition. The mutually consistent estimates of \nu provide compelling support for a continuous deconfined quantum-critical point.