Continuum in the Excitation Spectrum of the S=1 Compound CsNiCl_3

TL;DR

This paper investigates the excitation spectrum of CsNiCl_3, revealing discrepancies with existing models and proposing a new theoretical approach involving interchain interactions to better match experimental data.

Contribution

The study introduces a model with interchain interactions approximated by a staggered magnetic field, improving predictions of excitation continuum intensity and other properties.

Findings

The continuum intensity is about 5 times greater than previous predictions.

The gap is slightly higher and the correlation length is smaller than earlier estimates.

The proposed model accurately predicts the observed spectral features.

Abstract

Recent neutron scattering experiments on CsNiCl_3 reveal some features which are not well described by the nonlinear sigma model nor by numerical simulations on isolated S=1 spin chains. In particular, in real systems the intensity of the continuum of multiparticle excitations, at T=6K, is about 5 times greater than predicted. Also the gap is slightly higher and the correlation length is smaller. We propose a theoretical scenario where the interchain interaction is approximated by a staggered magnetic field, yielding to a correct prediction of the observed quantities.