Low Temperature Correlation Lengths of Bilayer Heisenberg AntiFerromagnets and Neutron Scattering

TL;DR

This paper calculates the low temperature correlation length and static structure factor for bilayer antiferromagnets, demonstrating methods to interpret neutron scattering data and measure correlation lengths via NMR.

Contribution

It provides a theoretical framework for extracting correlation lengths from neutron scattering and NMR experiments in bilayer antiferromagnets, enabling precise future measurements.

Findings

Neutron scattering can be used to measure correlation lengths despite intensity modulation.

Theoretical predictions align with experimental interpretation methods.

NMR can also be employed to determine the same correlation lengths.

Abstract

The low temperature correlation length and the static structure factor are computed for bilayer antiferromagnets such as YBa_2Cu_3O_6. It is shown that energy integrated two-axis scan in neutron scattering experiments can be meaningfully interpreted to extract correlation length in such bilayer antiferromagnets despite intensity modulation in the momentum perpendicular to the layers. Thus, precise measurements of the spin-spin correlation length can be performed in the future, and the theoretical predictions can be tested. It is also shown how the same correlation length can be measured in nuclear magnetic resonance experiments.