Investigation of the Magnetic Model in Multiferroic NdFe$_{3}$(BO$_{3}$)$_{4}$ by Inelastic Neutron Scattering

TL;DR

This study uses inelastic neutron scattering to analyze magnetic excitations in NdFe3(BO3)4, revealing the hybridization between 4f and 3d magnetism and its role in the multiferroic properties.

Contribution

It develops a magnetic model explaining the hybridization and anisotropy in NdFe3(BO3)4, integrating experimental data with theoretical calculations.

Findings

Identification of anti-crossing of Nd- and Fe-excitations

Observation of anisotropy gap at the antiferromagnetic zone center

Hybridization propagates Nd3+ anisotropy to Fe3+ network

Abstract

We performed inelastic neutron scattering measurements on single crystals of NdFe$_{3}$($^{11}$BO$_{3}$)$_{4}$ to explore the magnetic excitations, to establish the underlying Hamiltonian, and to reveal the detailed nature of hybridization between the 4$f$ and 3$d$ magnetism. The observed spectra exhibiting a couple of key features, i.e., anti-crossing of Nd- and Fe-excitations and anisotropy gap at the antiferromagnetic zone center, are explained by the magnetic model including spin interaction in the framework of weakly-coupled Fe$^{3+}$ chains, interaction between the Fe$^{3+}$ and Nd$^{3+}$ moments, and single-ion anisotropy derived from Nd$^{3+}$ crystal field. The combination of the measurements and calculations reveals that the hybridization between 4$f$ and 3$d$ magnetism propagates the local magnetic anisotropy of the Nd$^{3+}$ ion to the Fe$^{3+}$ network, resulting in the bulk structure of multiferroics.