Susceptibility of the 2D S=1/2 Heisenberg antiferromagnet with an impurity

TL;DR

This study investigates how magnetic and nonmagnetic impurities affect the magnetic susceptibility of a 2D S=1/2 Heisenberg antiferromagnet using quantum Monte Carlo simulations, revealing a low-temperature log-divergence and proposing an effective model.

Contribution

It introduces an effective few-spin model that accurately describes impurity effects across temperature ranges, enhancing understanding of impurity impacts in quantum antiferromagnets.

Findings

Log-divergent contribution to transverse susceptibility at low temperatures

Effective few-spin model captures impurity effects quantitatively

Differences between magnetic and nonmagnetic impurities characterized

Abstract

We use a quantum Monte Carlo method (stochastic series expansion) to study the effects of a magnetic or nonmagnetic impurity on the magnetic susceptibility of the two-dimensional Heisenberg antiferromagnet. At low temperatures, we find a log-divergent contribution to the transverse susceptibility. We also introduce an effective few-spin model that can quantitatively capture the differences between magnetic and nonmagnetic impurities at high and intermediate temperatures.