Quantum critical exponents of a planar antiferromagne

TL;DR

This paper provides high-precision estimates of quantum critical exponents in a planar antiferromagnet, supporting the universality class conjecture and showing the irrelevance of Berry phases for critical behavior.

Contribution

It introduces advanced cluster algorithms for quantum spin systems, enabling precise exponent estimation and confirming universality class predictions.

Findings

Quantum Heisenberg antiferromagnet shares universality class with O(3) nonlinear sigma model.

Berry phase effects are not relevant for the critical behavior.

High-precision critical exponents were obtained using loop algorithms.

Abstract

We present high precision estimates of the exponents of a quantum phase transition in a planar antiferromagnet. This has been made possible by the recent development of cluster algorithms for quantum spin systems, the loop algorithms. Our results support the conjecture that the quantum Heisenberg antiferromagnet is in the same universality class as the O(3) nonlinear sigma model. The Berry phase in the Heisenbrg antiferromagnet do not seem to be relevant for the critical behavior.