Paramagnetism in NiSe2

The magnetic properties of a pyrite compound NiSe 2 have been investigated by the 77 Se NMR, the magnetic susceptibility and the specific heat measurements in the temperature range between 1.6 and 300 K. The electronic specific heat coefficient, γ, is obtained to be (8.5±1.0) mJ/K 2 mol. The values of the magnetic susceptibility and the Knight shift are estimated to be 2.17×10 -4 emu/mol and +(1.0±0.1)%, respectively, both being independent of temperature. The product of the nuclear spin-lattice relaxation time and temperature, T 1 T , is found to be constant with a value or 240 msec K. From these results, it is concluded that NiSe 2 is one of the typical Pauli paramagnets and the usual Korringa relation holds with a relatively small exchange enhancement effect. Discussions of the origin of the hyperfine coupling constant of 77 Se are also given in conjunction with the reported result of CoSe 2 .