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.

在绝缘磁体中，宏观自旋输运性质与磁振子（magnons）密切相关。然而，声子（phonons）作为绝缘磁体中另一类基本元激发，其在自旋输运中的作用仍有待探索。近期有研究提出，在强自旋-晶格耦合作用下，磁振子与声子可发生杂化，在磁振子和声子能带的反交叉区域附近形成拓扑磁振子极化子（topological magnon polarons），并产生本征热霍尔效应与自旋能斯特效应（spin Nernst effects）。这种新型激发模式已在Fe₂Mo₃O₈中被观测到，并被归因于由Dzyaloshinskii-Moriya（DM）相互作用诱导的强磁振子-声子耦合。该新型激发是否可通过其他自旋-晶格耦合机制产生，仍有待实验验证。为解决上述问题，本研究拟对范德瓦尔斯（van der Waals）三角反铁磁体FeCl₂的激发光谱进行测量。