title: Resonating plaquette phase of a quantum six-vertex model.
abstract: The simplest quantum generalization of the six-vertex model describes fluctuations of the order parameter of the d-density wave (DDW), believed to compete with superconductivity in the high-T(c) superconductors. The ground state of this model undergoes a first order transition from the DDW phase to a resonating plaquette phase as the quantum fluctuations are increased, which is explored with the help of quantum Monte Carlo simulations and analytic considerations involving the n-vector (n = 2) model with cubic anisotropy. In addition to finding a new quantum state, we show that the DDW is robust against a class of quantum fluctuations of its order parameter. The inferred finite temperature phase diagram contains unsuspected multicritical points.
authors.affiliation: NORDITA, Blegdamsvej 17, DK-2100 Copenhagen Ø, Denmark.
authors.forename: Olav F
authors.initials: OF
authors.lastname: Syljuåsen
authors.forename: Sudip
authors.initials: S
authors.lastname: Chakravarty