Optical detection of 4-spin chiral interaction in a 2D honeycomb ferrimagnet

TL;DR

This paper proposes a novel optical method to detect 4-spin chiral interactions in 2D honeycomb ferrimagnets, specifically in Fe$_{3}$GeTe$_{2}$, which exhibit complex symmetry properties beyond traditional Dzyaloshinskii-Moriya interactions.

Contribution

It introduces an experimental approach to observe 4-spin chiral interactions via energy selective magnon relaxation in 2D ferromagnets with specific symmetry.

Findings

Identification of 4-spin chiral interactions in 2D honeycomb ferrimagnets.

Proposal of optical detection method using magnon relaxation.

Relevance to materials with D$_ extrm{3h}$ symmetry.

Abstract

Broken inversion symmetry of magnetic lattice is normally described by Lifshitz invariants in micromagnetic energy functional. Three exceptions are the lattices with T$_\textrm{d}$, C$_\textrm{3h}$ and D$_\textrm{3h}$ point group symmetries. The inversion symmetry breaking of the corresponding magnets is described by more complex 4-spin chiral invariants that cannot be related to Dzyaloshinskii-Moriya interaction. Experimental detection of 4-spin chiral interactions is an important task that has yet to be performed. We propose that the 4-spin chiral interaction can be probed by energy selective magnon relaxation in two-dimensional ferromagnet Fe$_{3}$GeTe$_{2}$ that possess D$_\textrm{3h}$ point group symmetry.