Thermodynamic properties of [Cu-II(en)(2)(H2O)][Cu-II(en)(2)Ni2Cu2I(CN)(10)]center dot 2H(2)O-S=1/2 magnet with a layered crystal structure

The specific heat of [Cu-II (en)(2)(H2O)][Cu-H (en)(2)Ni2Cu21(CN)(10)] . 2H(2)O was measured in the temperature range from 1.5 K to 10 K. The studies did not reveal any phase transition into an ordered state. Magnetization measurements, at 4.2 K and 13.7 K and in fields up to 60 kG, confirmed the assumption of weak exchange interactions, resulting from the knowledge of the crystal structure. Magnetic susceptibility data show deviations from Curie-Weiss law near 5.5 K. The analysis of the inverse susceptibility data indicates the presence of antiferromagnetic exchange coupling J/k(B) approximate to -0.65 K.