Abstract
Magnetic measurements were performed on the specimens of powdered and single crystals of nickel sulfide having the structure of nickel arsenide type. From the results of measurements of the susceptibility, specific heat and other data, it was found that nickel sulfide is antiferromagnetic with the Néel point at 150°K. However, below 120°K, the susceptibility of the powder specimen increased with the fall of temperature and also showed a dependence of magnetic field. Such a rise in susceptibility at lower temperatures is here interpreted as due to the influence of paramagnetic islands. Correction for the atom core diamagnetism was applied to the observed susceptibilities, and from the inverse susceptibility vs temperature relation, the Curie constant per mol, CM, the spin quantum number, S, and the asymptotic Curie temperature, θ, were obtained as 0.89, 1.9/2 and ca 3000° respectively. From the torque measurement of a single crystal of this compound, it was seen that the antiferromagnetic easy direction lies in (0001) plane of the crystal.
