Asymptotic scaling of the square lattice quantum Heisenberg antiferromagnet

TL;DR

This paper uses quantum Monte Carlo simulations to measure thermodynamic properties of the 2D S=1/2 quantum Heisenberg antiferromagnet on a square lattice, confirming theoretical predictions and resolving debates about its crossover behavior.

Contribution

It provides the first precise thermodynamic measurements of the model's infinite-volume limit, validating chiral perturbation theory and clarifying the quantum critical to classical crossover.

Findings

Uniform susceptibility matches theoretical asymptotic behavior

Crossover from quantum critical to classical regime is confirmed

Quantum Monte Carlo effectively captures thermodynamic limits

Abstract

We present thermodynamic measurements of various physical observables of the two dimensional S=1/2 isotropic quantum Heisenberg antiferromagnet on a square lattice, obtained by quantum Monte Carlo. In particular we have been able to measure the infinite volume limit of the uniform susceptibility up to the inverse temperature beta=40, the analysis of which reveals the correct asymptotic behavior in excellent agreement with the prediction of chiral perturbation theory. The controversy over the existence of a crossover from quantum critical to renormalized classical regime is resolved.