Suppression of the Metal Instability and Continuous Change of the Carrier Density in (MeBr-DCNQI)2Cu1−xLix

Abstract
Electrical resistivities and IR spectra of new mixed cation (Cu/Li)-DCNQI systems were examined. (MeBr-DCNQI)2Cu1−xLix (0.25 < x < 0.5) remains in the metallic state down to 4 K. The stretching frequency of C=N(imine) of DCNQI shows a linear dependence on the charge of DCNQIf which is consistent with the mixed valency of Cu (Cu+1.3).