NMR Investigations of the Microscopic Magnetic Properties of CoS₂

Abstract

The magnetic properties of the metallic compound CoS₂ have been studied microscopically using the cw and pulsed NMR techniques in both the paramagnetic and the ferromagnetic states. The ⁵⁹Co Knight shift is shown to be in linear relation with the uniform susceptibility with a hyperfine coupling constant of −148.6 kOe/spin. The d-spin susceptibility χ_d derived from the Knight shift measurements is found to obey the Curie-Weiss law above 420 K with the effective moment corresponding to one electron per Co atom, while the slope in the 1/χ_d vs T plot below 420 K is smaller than that above 420 K. The temperature and external field dependences of the NMR frequency in the ferromagnetic state have also been measured in detail. The results of our measurements are in accord with the predictions based on the general theory of spin fluctuations and yield a conclusion that CoS₂ can be classified as a nearly saturated narrow band ferromagnet.