Hexagonal HoMnO3, a two-dimensional Heisenberg antiferromagnet, has been studied via inelastic neutron scattering. A simple Heisenberg model with a single-ion anisotropy describes most features of the spin-wave dispersion curves. However, there is shown to be a renormalization of the magnon energies located at around 11 meV. Since both the magnon-magnon interaction and magnon-phonon coupling can affect the renormalization in a noncollinear magnet, we have accounted for both of these couplings by using a Heisenberg XXZ model with 1=S expansions [1] and the Einstein site phonon model [13], respectively. This quantitative analysis leads to the conclusion that the renormalization effect primarily originates from the magnon-phonon coupling, while the spontaneous magnon decay due to the magnon-magnon interaction is suppressed by strong two-ion anisotropy.
@article{arxiv.1805.08919,
title = {Renormalization of spin excitations in hexagonal HoMnO3 by magnon-phonon coupling},
author = {Taehun Kim and Jonathan C. Leiner and Kisoo Park and Joosung Oh and Hasung Sim and Kazuki Iida and Kazuya Kamazawa and Je-Geun Park},
journal= {arXiv preprint arXiv:1805.08919},
year = {2018}
}