Electron spin dynamics in the new halogen-bridged one-dimensional complex, Ni₂(CH₃CS₂)₄I studied by ¹H NMR

We measured temperature and Larmor frequency(ω) dependences of the ¹H NMR spin-lattice relaxation time T₁ in solid Ni₂(CH₃CS₂)₄I which contains the one-dimensional(1-D) chain of -Ni-Ni-I-Ni-Ni-I- with no Peierls distortion. Almost temperature independent T₁ values of ca. 180 ms observed at ω = 40.98 MHz and in the range of 90-300 K are attributable to the relaxation due to the fluctuation of antiferromagnetically coupled unpaired electron spin formed at each -X-Ni-Ni- unit in consistent with the 1-D Mott-Hubbard type structure. T₁ in this temperature range showed the Larmor frequency dependence of ω ^{1 2} explainable by rapid spin diffusion along the 1-D chain. Applying the Devreux's treatment on the low-dimensional spin dynamics, the diffusion rate and activation energy for the 1-D hopping of electron spins were evaluated.