Single-ion versus two-ion anisotropy in magnetic compounds: A neutron scattering study

TL;DR

This study introduces a neutron scattering technique to distinguish between single-ion and two-ion anisotropy effects in magnetic materials, demonstrated on manganese clusters, revealing dominant single-ion anisotropy.

Contribution

The paper presents a direct method using neutron spectroscopy to differentiate and analyze anisotropy types in magnetic compounds, enhancing understanding of magnetic ground states.

Findings

Anisotropy is approximately 3% of exchange interaction.

Single-ion anisotropy dominates over two-ion anisotropy.

Method effectively characterizes magnetic cluster excitations.

Abstract

Anisotropy effects can significantly control or modify the ground-state properties of magnetic systems. Yet the origin and the relative importance of the possible anisotropy terms is difficult to assess experimentally and often ambiguous. Here we propose a technique which allows a very direct distinction between single-ion and two-ion anisotropy effects. The method is based on high-resolution neutron spectroscopic investigations of magnetic cluster excitations. This is exemplified for manganese dimers and tetramers in the mixed compounds CsMnxMg1-xBr3 (0.05\leqx\leq0.40). Our experiments provide evidence for a pronounced anisotropy of the order of 3% of the dominant bilinear exchange interaction, and the anisotropy is dominated by the single-ion term. The detailed characterization of magnetic cluster excitations offers a convenient way to unravel anisotropy effects in any magnetic material.