S(k) for Haldane Gap Antiferromagnets: Large-scale Numerical Results vs. Field Theory and Experiment

TL;DR

This paper uses large-scale numerical simulations to accurately compute the structure function S(k) for Haldane gap antiferromagnets, confirming theoretical predictions and aligning with experimental results.

Contribution

It provides detailed numerical results for S(k) in s=1 chains, validating field theory and experimental data with high precision.

Findings

Excellent agreement between DMRG results and nonlinear sigma model predictions.

Consistent results with experimental data for NENP material.

Determination of correlation lengths, gaps, and velocities for different polarizations.

Abstract

The structure function, S(k), for the s=1, Haldane gap antiferromagnetic chain, is measured accurately using the recent density matrix renormalization group method, with chain-length 100. Excellent agreement with the nonlinear $\sigma$ model prediction is obtained, both at $k\approx \pi$ where a single magnon process dominates and at $k\approx 0$ where a two magnon process dominates. We repeat our calculation with crystal field anisotropy chosen to model NENP, obtaining good agreement with both field theory predictions and recent experiments. Correlation lengths, gaps and velocities are determined for both polarizations.