The zero-field susceptibilities parallel and perpendicular to the tetragonal axis of NiCl2⋅4SC(NH2)2 have been measured between 1.2 and 30 K and fitted to the usual spin Hamiltonian. The resulting parameters are D/kB = 7.6±0.4 K, z0J/kB = −4.5±0.3 K, g∥ = 2.26±0.03 and g⊥ = 2.34±0.03. The susceptibility has also been measured parallel to the tetragonal axis at constant temperatures between 0.3 and 2 K as a function of external field. Magnetic ordering is found to occur, and portions of the phase boundary between paramagnetic and antiferromagnetic states have been determined.
The characterization of Co(urea)2Cl2⋅2H2O is reported. The crystal structure at ambient temperatures yields the following information: the chlorine, water, and urea group are coordinated, the urea being bound via the oxygen, to form an octahedral environment about the metal atom. Intermolecular hydrogen bonds between the coordinated chlorine and water ligands produce parallel infinite sheets which provide a two-dimensional exchange pathway. The sheets are separated by the urea ligands and may be considered as magnetically isolated from one another. Crystal data: space group P21/c, Z = 2, a = 7.397 (3) Å, b = 7.795(1) Å, c = 9.764(2) Å, β = 116.23(5) Å, V = 505 Å3, ρcalc = 1.87 g cm−3, ρobs = 1.88 g cm−3, R = 4.1% for 692 reflections. A λ anomaly in the specific heat was observed at 2.585±0.005 K, and the critical parameters are characteristic of the two-dimensional Ising model. The zero-field susceptibilities have been measured over the temperature interval 1.2–30 K, and are consistent with antiferromagnetic ordering at 2.52±0.05 K. The easy axis lies parallel to the monoclinic a axis, while hidden canting was observed parallel to the b axis. All the data have been analyzed consistently by the two-dimensional Ising model with the parameters ga = 7.0±0.1, J/kB = −2.1±0.05 K.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.