Cu NMR and NQR Study of CuS

We report Cu NMR and NQR studies of the cupric sulfide CuS from 4.2 K to room temperature. We have assigned the site for two distinct 63 Cu NMR lines based on an abrupt change of the Cu NMR spectrum at 55 K due to a structural phase transition for both the powder and the oriented CuS. We found that the Cu nuclear spin-lattice relaxation rate 1/ T 1 is magnetic in origin and highly anisotropic, and that the temperature dependence of 1/ T 1 T is similar to that of the uniform magnetic susceptibility χ 0 ( T ). The orbital contribution to the relaxation rate and the nature of the electron spin correlation at the Cu sites are discussed.