Resonating plaquette phase of a quantum six-vertex model

TL;DR

This paper investigates a quantum six-vertex model revealing a transition from a d-density wave phase to a resonating plaquette phase, with implications for high-temperature superconductivity and complex phase diagrams.

Contribution

It identifies a new resonating plaquette quantum phase and demonstrates the robustness of the DDW phase against certain quantum fluctuations.

Findings

First order transition from DDW to resonating plaquette phase

Discovery of a new quantum state with a resonating plaquette structure

Finite temperature phase diagram with multicritical points

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-Tc 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.