NMR Measurements in the Paramagnetic State of Uranium-Phosphorus Compounds. I. Line Shifts ofP31in UP and inUP1−xSx

NMR line shifts $\Delta H$ of ${}_{}{}^{31}{}_{}{}^{}\mathrm{P}$ in the antiferromagnetic semimetal UP and in its solid solutions $\mathrm{U}{\mathrm{P}}_{1-x}{\mathrm{S}}_x$ ($x\simeq 0,\frac{1}{4},\frac{1}{2},\frac{3}{4}$) in the paramagnetic state are proportional to the magnetization of the solid: $K=\frac{\Delta H}{H}=K_0+\alpha {\chi }_M$, where the parameters are nearly independent of composition $x$ and fall within a narrow range $K_0=(-35\mathrm{}\pm 15)\times {10}^{-4\mathrm{}}$; $\alpha =5.2\mathrm{}\pm 0.5$ ${\mathrm{}(\mathrm{e}\mathrm{m}\mathrm{u}/\mathrm{m}\mathrm{o}\mathrm{l}\mathrm{e})\mathrm{}}^{-1\mathrm{}}$. This line shift is interpreted as superhyperfine (shf) polarization transferred through U-P bonds, where the shf coupling constants are $A_s=-32.4\mathrm{}\pm 1.0$ MHz and $A_p=+3.6\mathrm{}\pm 0.6$ MHz. Although the U-U magnetic coupling is carried by conduction electrons (Ruderman-Kittel-Kasuya-Yosida interaction), the U-P magnetic coupling is through bonds of localized electrons. The results are compared with NMR line shifts in rare-earth monopnictides and with electron-nuclear double-resonance experiments on rare-earth ions.