Low-energy magnetic excitations of the easy-axis antiferromagnet TbFe3(BO3)4 are investigated by far-infrared absorption and reflection spectroscopy in high magnetic fields up to 30 T. The observed field dependence of the resonance frequencies and the magnetization are reproduced by a mean-field spin model for magnetic fields applied both along and perpendicular to the easy axis. Based on this model we determined the full set of magnetic interactions, including Fe-Fe and Fe-Tb exchange interactions, single-ion anisotropy for Tb ions and g-factors, which describe the ground-state spin texture and the low-energy spin excitations of TbFe3(BO3)4. Compared to earlier studies we allow a small canting of the nearly Ising-like Tb moments to achieve a quantitative agreement with the magnetic susceptibility measurements. The additional high energy magnetic resonance lines observed, besides the two resonances expected for a two-sublattice antiferromagnet, suggest a more complex six-sublattice magnetic ground state for TbFe3(BO3)4.
@article{arxiv.1610.04455,
title = {Magnetic resonances of multiferroic TbFe$_3$(BO$_3$)$_4$},
author = {Dávid Szaller and Vilmos Kocsis and Sándor Bordács and Titusz Fehér and Toomas Rõõm and Urmas Nagel and Hans Engelkamp and Kenya Ohgushi and István Kézsmarki},
journal= {arXiv preprint arXiv:1610.04455},
year = {2017}
}