Charge-Transfer-Controlled Phase Transition in a Molecular Conductor, (DMe-DCNQI)_2Cu---Doping Effect---

抄録

Li⁺-doping in the Cu salt of deuterated DMe-DCNQI-d₇ has shown drastic effects on electrical and magnetic properties. Undoped (DMe-DCNQI-d₇)₂Cu exhibits a first-order metal-insulator (M-I) transition at 80, K. A small amount of Li⁺-doping suppresses the M-I transition. The M-I-M (reentrant) transition, which is similar to that in selectively deuterated (DMe-DCNQI)₂Cu, appears in a narrow region of Li content x. The x-T phase diagram under ambient pressure well reproduces the P-T phase diagram of the (DMe-DCNQI)₂Cu system. This doping effect is explained by the change in charge transfer amount from metal ions to DCNQI molecules. The effect of pressure or deuteration on the M-I transition in the DCNQI₂Cu system is generally understood from this viewpoint.