Ground States of DCNQI-Metal Complexes, (R1,R2-DCNQI)2M; (R1,R2 = CH3, I, M = Ag, Cu, Li1−xCux)

Abstract

Abstract The electrical resistance, magnetic susceptibility, 1H-and 13C-NMR measurements have been performed to investigate the ground states of the metal complexes of DCNQI, (R1,R2-DCNQI)2M, where R1(R2) is CH3 (Me) or iodine (I) and M is Ag, Cu or Li1-xCux. A new member of DCNQI-M complexes, (DI-DCNQI)2Ag, is nonmetallic below room temperature and shows a Bonner-Fisher type of susceptibility, of which the value is nealy the same as that of (DI-DCNQI)2Cu at room temperature. An antiferromagnetic ordering was found at 5.5K in contrast to the spin-Peierls ground state in the isostructural (DMe-DCNQI)2Ag. The alloy systems, (DMe-DCNQI)2Li1−xCux, have been studied with an aim at control of the electronic state by the doping of Cu into the insulator, (DMe-DCNQI)2Li. For the Cu doping up to x=30%, the systems show the spin-Peierls transition while the system with x>50% are metallic down to low temperatures. The (T 1 T)−1 of 13C-NMR shows systematic change with doping.