Crystal Field, Magnetic Anisotropy and Excitations in Rare-Earth Hexaborides

TL;DR

This paper investigates the effects of crystalline electric fields on magnetic anisotropy and excitations in cubic rare-earth hexaborides, with a focus on NdB_6, revealing non-collinear magnetization and mode suppression.

Contribution

It provides a detailed analysis of CEF effects and spin-quadrupolar coupling in NdB_6, predicting specific excitation behaviors and ground-state magnetization configurations.

Findings

Identification of non-collinear magnetization in NdB_6

Prediction of magnetic mode suppression in strong coupling

Analysis of CEF scheme and spin-quadrupolar effects

Abstract

We clarify the role of crystalline electric field (CEF) induced magnetic anisotropy in the ground state and spin-wave spectrum of cubic rare-earth materials with dominating isotropic magnetic exchange interactions. In particular we study the hexaboride NdB_6 which is shown to exhibit strong spin-quadrupolar coupling. The CEF scheme is analyzed and a non-collinear magnetization response is found. The spin orientation in the antiferromagnetically ordered ground-state is identified. Moreover, the spin excitations are evaluated and in agreement with inelastic neutron scattering a suppression of one of the two magnetic modes in the strong-coupling regime is predicted.