Dynamic spin fluctuations in the molecular ferromagnet (DMeFc)(TCNE)

The static and dynamic magnetic properties of the molecular ferromagnet decamethylferrocenium tetracyanoethenide (DMeFc)(TCNE) are studied via the muon-spin-relaxation technique. Spontaneous order is observed in the ferromagnetic ground state below 5 K, while the muon-spin-relaxation rate in the paramagnetic phase displays a gradual variation with temperature, indicating that a slowing down of spin fluctuations occurs over a wide temperature range. The temperature dependence of spin fluctuations between 8 and 80 K shows the thermally activated behavior expected in a spin chain with Ising character.