Thermodynamic Property of 1D Strongly Correlated Charge-Ordered Complex, (DI-DCNQI)2Ag under Pressures

We have measured the heat capacities of organic charge transfer salts of (DI-DCNQI)2Ag by the ac-modulation technique under pressures and magnetic fields. In this salt, the DCNQI molecules stack along the c-axis and form one-dimensional conducting columns in this direction. These 1D columns are bridged by monovalent metal cation M = Ag through a CN-M coordination bond. (DI-DCNQI)2Ag forms a charge-ordered state around 220 K and shows antiferromagnetic order around 6 K. We have observed that the heat capacities are reduced gradually under pressures of 5 kbar, 10 kbar, and 16 kbar, which suggests that the charge-ordered state is suppressed by applying pressures. External pressure is useful parameter for studying these organic charge transfer salts.

(by N. Tokoro & Y. Nakazawa)

	Fig. 1. Cp T−1 vs. T2 plot of (DI-DCNQI)2Ag at ambient pressure and under pressure of 5 kbar. We can see reduction of the heat capacity with increasing pressures. This tendency is consistent with the picture that the external pressure suppresses the charge-ordered state.
	Fig. 2. Cp T−1 vs. T2 plot of (DI-DCNQI)2Ag under pressure of 10 kbar and 16 kbar. The field dependence of the heat capacities with applying pressures is observed.