Nickel Sulfide—an Itinerant-Electron Antiferromagnet

Abstract

Antiferromagnetic nickel sulphide has a small temperature-independent magnetic susceptibility. The ordered moment per nickel atom, measured with neutrons, decreases from ${1.45\mathrm{\ensuremath{\mu}}}_{\mathrm{B}}$ to ${1.00\mathrm{\ensuremath{\mu}}}_{\mathrm{B}}$ at 4.2 K with a decrease of 0.6% in the Ni-Ni distance. These data indicate a band model for the $n$ electrons, making NiS an itinerant-electron antiferromagnet with no local moments. The possibility of local moments in an antiferromagnetic metal is briefly discussed.