Multispinon continua at zero and finite temperature in a near-ideal Heisenberg chain

TL;DR

This paper demonstrates that advanced theoretical methods can accurately describe the dynamical response of a quantum spin chain at various temperatures, validated by neutron scattering experiments on KCuF3.

Contribution

It provides a detailed comparison between experimental data and state-of-the-art theoretical calculations for the dynamical structure factor in a Heisenberg chain, showing unprecedented quantitative agreement.

Findings

Excellent match between neutron scattering data and theoretical models.

Validation of integrability-based and DMRG methods for quantum magnetism.

Demonstration of precise descriptions of strongly correlated states across temperature scales.

Abstract

The space- and time-dependent response of many-body quantum systems is the most informative aspect of their emergent behaviour. The dynamical structure factor, experimentally measurable using neutron scattering, can map this response in wavevector and energy with great detail, allowing theories to be quantitatively tested to high accuracy. Here, we present a comparison between neutron scattering measurements on the one-dimensional spin-1/2 Heisenberg antiferromagnet KCuF3, and recent state-of-the-art theoretical methods based on integrability and density matrix renormalization group simulations. The unprecedented quantitative agreement shows that precise descriptions of strongly correlated states at all distance, time and temperature scales are now possible, and highlights the need to apply these novel techniques to other problems in low-dimensional magnetism.