Ultrafast magnetization and structural dynamics in the intercalated transition metal dichalcogenides Fe_0.25TaS₂ and Mn_0.25TaS₂

We measure magnetization and structural dynamics in two intercalant-ordered transition metal dichalcogenides: Fe_0.25TaS₂ and Mn_0.25TaS₂. The structurally equivalent materials allow us to probe the effect of orbital angular momentum which is active in Fe_0.25TaS₂ and absent in Mn_0.25TaS₂. Interestingly, we find that the magnetooptics dynamics are nearly indistinguishable in these two materials, in contradiction to conventional explanations of a spin-lattice mechanism. We compare our results to other materials where spin-lattice demagnetization has been put forth as a demagnetization channel.