An experimental measurement of the staggered magnetization curve for a Haldane spin chain

TL;DR

This paper presents experimental measurements of the staggered magnetization curve in Haldane spin chains within certain quasi-one-dimensional antiferromagnetic compounds, combining experimental data with a mean-field theoretical model.

Contribution

It introduces a mean-field model based on the intrinsic staggered magnetization of isolated Haldane chains and applies it to new and existing experimental diffraction data.

Findings

Extracted the bare staggered magnetization curve for Haldane chains.

Validated the mean-field model against experimental data.

Provided insights into magnetic ordering in R_2 Ba Ni O_5 compounds.

Abstract

Long-range magnetic ordering in R_2 Ba Ni O_5 (R=magnetic rare earth) quasi-1-dimensional mixed-spin antiferromagnets is described by a simple mean-field model that is based on the intrinsic staggered magnetization function of isolated Haldane spin chains for the Ni-subsystem, and single-ion magnetization functions for the rare earth ions. The model is applied to new experimental results obtained in powder diffraction experiments on Nd_2 Ba Ni O_5 and Nd Y Ba Ni O_5, and to previously published diffraction data for Er_2 Ba Ni O_5. From this analysis we extract the bare staggered magnetization curve for Haldane spin chains in these compounds.