Progress of Theoretical Physics Supplement
Weak First-Order Superfluid-Solid Quantum Transitions and Deconfined Criticality
Anatoly B. Kuklov, Nikolay V. Prokof'ev, Boris V. Svistunov
Abstract
We examine recent theoretical predictions for two-dimensional lattice bosonic/spin systems that superfluid-solid (SF-S) quantum phase transitions are often continuous and do not fit the canonical Ginzburg-Landau-Wilson (GLW) picture.We show that the GLW theory based on extended broken symmetry is consistent with existing numerical data, which report weak first-order transitions or problems with the finite-size scaling.This GLW theory excludes generic continuous SF-S transitions and quantum disordered phases.Remarkably, the phase diagram of the deconfined critical action itself features a weak first-order phase transition with spinon deconfinement, in accordance with the conventional theory.Problems with data collapse even in the regime of weak interactions between the spinons strongly suggest that the first-order deconfinement transition is the only possible outcome. * )Since the first study of the SF-VBS point within the J-current model, we have observed numerous first-order SF-VBS transitions for different sets of Hamiltonian parameters.