1H-NMR studies of (DMe-DCNQI-d7)2Cu1 − xLix

Systematic measurements of 1H-NMR relaxation rate, T1−1, in the organic conductor, (DMe-DCNQI-d7)2Cu1 − xLix (x = 0.04, 0.5 ∼ 0.6, 1), have been carried out, to clarify the effect of Li doping on the electronic properties of pπ-band. Within the stable metallic region (up to about x = 0.5), T1−1 exhibits a Korringa-like behavior, (T1T)−1 = const. In a highly doped sample, a nonmetallic phase appears at low temperatures. The absolute value of T1−1 in the metallic region increases remarkably with the Li concentration and becomes the largest in the pure Li-salt, (DMe-DCNQI-d7)2Li. This behavior is analyzed as a low-dimensional spin-diffusion effect.