M. Orendac et al., ON THE LOW-TEMPERATURE SPECIFIC-HEAT OF NI(EN)2NI(CN)4 AND NI(EN)2NI(CN)4.2.5H2O, IEEE transactions on magnetics, 30(2), 1994, pp. 1109-1111
Specific heat measurements on Ni(en)2Ni(CN)4 (where en=C2H8N2) and Ni(
en)2Ni(CN)4 . 2.5H2O in the temperature region from 60 mK to 10 K are
presented. No indication of a three-dimensional ordering is observed d
own to 60 mK. Both compounds appear to be good representatives of anti
ferromagnetic S=1 Heisenberg linear chain systems with D/k=6 K, D/\J\=
10 and D/k=6.3 K, D/1.\J\=50, respectively.