Spin correlation and relaxational dynamics in molecular-based single-chain magnets

We report the combined measurements of the dc susceptibility χ0, the ac susceptibility χ′, and the NMR relaxation rate T1 -1 for the molecular-based heterometallic single-chain magnet [Mn (saltmen)] 2 [Ni (pao)2 (py)2] (P F6) 2. At low temperatures, this system is well described by a one-dimensional array of effective spin S=3 chains comprising the MnIII - NiII - MnIII trimers and treated as the S=3 Ising chain with the single-ion term (Blume-Capel model). Using the exact solution of the model and based on the picture that the random motion of the local domain walls dominates the low-temperature spin dynamics, we succeeded in reproducing the experimental results of the dc susceptibility χ0, the ac susceptibility χ′, and the F19 -NMR relaxation rate T1 -1 in a consistent manner.