ENHANCED MAGNETIC-SUSCEPTIBILITY OF (DI-DCNQI)(2)CU

The Cu salt of 2,5-diiodo-N,N'-dicyanoquinonediimine, (DI-DCNQI)(2)Cu, which is metallic down to 4 K, is found to exhibit enhanced and tempe rature dependent magnetic susceptibility, in contrast to other metalli c DCNQI salts of Cu. The susceptibility shows a broad maximum around 1 10 K. The temperature dependence can be analyzed on the basis of a phe nomenology using a characteristic temperature, T approximate to 200 K . This suggests an important role of spin fluctuations in a narrow 3d band near the Fermi level. To our knowledge, this is the first evidenc e for the effect of spin fluctuation in a molecular conductor based on pi-d interactions.