Synthetic Metals

Anisotropic metallic character of C6Li from CESR

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Conduction electron spin resonance (CESR) of C6Li intercalates from highly oriented pyrolytic graphite was investigated between 100 and 300 K with the external magnetic field parallel and perpendicular to the c-axis. The g-values were found to be essentially temperature independent and close to the free electron value: g∥ = 2.0023, g⊥ = 2.0031 ± 0.0002. A strong anistropy of the asymmetry ratios (A/B)∥ and (A/B)⊥ was observed. Both quantities decrease significantly upon cooling, in contrast to the C8M (M = K, Rb, Cs) compounds. For the Ho∥ c orientation, the Bloembergen (slow-diffusion) limit of the Dysonian line shape is already reached in the vicinity of 250 K. We infer that the diffusion time along the c-axis is longer than 1 μs below this temperature. Compared to its C8M counterparts, C6Li appears much more two-dimensional at low temperatures, while room temperature ESR and d.c. transport anisotropies are known to behave in the opposite way. © 1983.