title: Spin ordering and enhancement of electronic heat capacity in an organic system of (DI-DCNQI)(2)(Ag(1-x)Cu(x)).
abstract: Thermodynamic measurements on the organic system of (DI-DCNQI)(2)(Ag(1-x)Cu(x)) (x = 0,0.05, 0.71, 0.90) were performed to study the change from the charge-ordered (CO) insulating state to the π-d hybridized metallic state. A thermal anomaly associated with the antiferromagnetic transition that occurred in the charge-ordered lattice was observed at 6.2 K from the temperature dependence of the heat capacity of (DI-DCNQI)(2)Ag. We have found that the magnetic entropy around the peak is only 1.5% of Rln2, corresponding to the full entropy expected for the formula unit of (DI-DCNQI)(2)Ag. This anomaly is suppressed down to about 3 K in the x = 0.05 sample owing to the disorders induced in the CO lattice. In the metallic concentration of x = 0.90, the low-temperature electronic heat capacity coefficient, γ was found to be enhanced by up to about 63.6 mJ K(-2) mol(-1) probably owing to the cooperative effect of π-d hybridization and intersite Coulomb interaction (V).
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan. Department of Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, Meguro-Ku, Tokyo 152-8550, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Okuma
authors.forename: S
authors.initials: S
authors.lastname: Yamashita
authors.forename: Y
authors.initials: Y
authors.lastname: Nakazawa
authors.forename: M
authors.initials: M
authors.lastname: Oguni
authors.forename: K
authors.initials: K
authors.lastname: Miyagawa
authors.forename: K
authors.initials: K
authors.lastname: Kanoda