Investigating the hybrid excitations in a van der Waals triangular magnet

In insulating magnets, the macroscopic spin transport properties are close related to magnons. However, phonons, as another fundamental type of elementary excitations in insulating magnets, still have their role in spin transport waiting to be explored. Recently, it has been proposed that magnons and phonons can hybridize under strong spin-lattice coupling to form topological magnon polarons near the anticrossing regions of magnon and phonon bands and result in intrinstic thermal Hall and spin Nernst effects. This novel excitation has been observed in Fe2Mo3O8 and has been attributed to strong magnon-phonon coupling induced by Dzyaloshinskii-Moriya (DM) interaction. Whether this novel excitation can arise through other spin-lattice coupling mechanisms remain to be experimentally verified. To address these questions, we propose to measure the excitation spectra of a van der Waals triangular antiferromagnet FeCl2.