Quantum criticality in a dissipative (2+1)-dimensional XY model of circulating currents in high-Tc cuprates

TL;DR

This paper uses large-scale Monte Carlo simulations to analyze a (2+1)-dimensional quantum XY model with bond dissipation, revealing a dynamical critical exponent of approximately 1 and isotropic correlation functions, challenging previous marginal Fermi liquid findings.

Contribution

It provides the first detailed numerical analysis of the dynamical critical behavior of a dissipative quantum XY model relevant to high-Tc cuprates, showing isotropic correlations and a critical exponent of about 1.

Findings

Dynamical critical exponent z ≈ 1

Correlation functions are isotropic in space and imaginary time

Fluctuation spectrum involves momentum and frequency equally

Abstract

We present large-scale Monte Carlo results for the dynamical critical exponent z and the spatio-temporal two-point correlation function of a (2+1)-dimensional quantum XY model with bond dissipation, proposed to describe a quantum critical point in high-Tc cuprates near optimal doping. The phase variables of the model, originating with a parametrization of circulating currents within the CuO_2 unit cells in cuprates, are compact, {\theta_{r,\tau}} \in [-\pi,\pi>. The dynamical critical exponent is found to be z \approx 1, and the spatio-temporal correlation functions are explicitly demonstrated to be isotropic in space-imaginary time. The model thus has a fluctuation spectrum where momentum and frequency enter on equal footing, rather than having the essentially momentum-independent marginal Fermi liquid-like fluctuation spectrum previously reported for the same model.