Magnetic Properties of Plutonium Monophosphide

Abstract

The results of magnetization and NMR measurements of plutonium monophosphide are reported. A paramagnetic moment of $1.06{\mu }_B$ was obtained from the ${\chi }^{-1\mathrm{}}$-versus-$T$ plot, above the Curie temperature of 126°K, after subtracting a value of 190×${10}^{-6\mathrm{}}$ emu/mole for the temperature-independent orbital paramagnetism. A ferromagnetic moment of $0.42{\mu }_B$ per formula unit was obtained for PuP. The Knight shift of ${\mathrm{P}}^{31}$ in PuP is linearly dependent on the magnetic susceptibility above the Curie temperature. An effective hyperfine field of - 51 kG was determined from the slope of the $K$-versus-$\chi$ curve. The relaxation rate can be described in terms of the Knight shift $K\equiv K_{\mathrm{PuP}}-K_{\mathrm{ThP}}$ by ${\left(T_{1}T\right)}^{-1\mathrm{}}=(23.5\mathrm{}\pm 1.7)\times {10}^{2}K$ ${\left(\mathrm{s}\mathrm{e}\mathrm{c}\mathrm{°}\mathrm{K}\right)}^{-1\mathrm{}}$. The saturation moment is discussed in terms of the localized-$5f$-electron model, and the NMR results are discussed in terms of the coupling of the conduction electrons and the localized $5f$ electrons.