In-plane magnetocrystalline anisotropy in the van der Waals antiferromagnet FePSe$_3$ probed by magneto-Raman scattering

TL;DR

This study investigates the in-plane magnetocrystalline anisotropy in FePSe$_3$ layered antiferromagnet using magneto-Raman scattering, revealing magnon-phonon coupling, mode splitting, and temperature-dependent tunability of excitations.

Contribution

It provides new insights into the in-plane anisotropy and magnon-phonon interactions in FePSe$_3$, highlighting the biaxial magnetic character and excitation tunability.

Findings

Magnon excitation split into two components coupled to phonons

Degeneracy lifting indicates biaxial anisotropy

Temperature affects the coupled mode character

Abstract

Magnon gap excitations selectively coupled to phonon modes have been studied in FePSe$_3$ layered antiferromagnet with magneto-Raman scattering experiments performed at different temperatures. The bare magnon excitation in this material has been found to be split (by $\approx~1.2$ cm$^{-1}$) into two components each being selectively coupled to one of the two degenerated, nearby phonon modes. Lifting the degeneracy of the fundamental magnon mode points out toward the biaxial character of the FePS$_3$ antiferromagnet, with an additional in-plane anisotropy complementing much stronger, out-of-plane anisotropy. Moreover, the tunability, with temperature, of the phonon- versus the magnon-like character of the observed coupled modes has been demonstrated.