Theoretical analysis of the experiments on the double-spin-chain compound -- KCuCl$_3$

TL;DR

This paper provides a theoretical analysis of susceptibility data for KCuCl3 using double-spin-chain models, employing advanced quantum Monte Carlo methods to match experimental results and predict interaction parameters.

Contribution

It introduces large-scale quantum Monte Carlo calculations for frustrated spin systems by removing the negative-sign problem using a dimer basis, achieving high accuracy in modeling KCuCl3.

Findings

Numerical data agree with experimental susceptibility within 1%

Theoretical dispersion relation matches neutron-scattering data

Predicted magnitudes of interaction bonds in KCuCl3

Abstract

We have analyzed the experimental susceptibility data of KCuCl$_3$ and found that the data are well-explained by the double-spin-chain models with strong antiferromagnetic dimerization. Large quantum Monte Carlo calculations were performed for the first time in the spin systems with frustration. This was made possible by removing the negative-sign problem with the use of the dimer basis that has the spin-reversal symmetry. The numerical data agree with the experimental data within 1% relative errors in the whole temperature region. We also present a theoretical estimate for the dispersion relation and compare it with the recent neutron-scattering experiment. Finally, the magnitude of each interaction bond is predicted.