Nuclear Magnetic Resonance in Uranium Hydride and Deuteride

$\beta$-uranium-hydride and $\beta$-uranium-deuteride are ferromagnetic with Curie temperatures of 182 and 178°K, respectively. Nuclear-magnetic-resonance studies of the proton in $\beta$-U${\mathrm{H}}_3$, and of the deuteron in $\beta$-U${\mathrm{D}}_3$, were made in the paramagnetic state of these compounds. The measured hydrogen Knight shifts ($K$) in $\beta$-U${\mathrm{H}}_3$ and $\beta$-U${\mathrm{D}}_3$ are given by $K=(0.40\mathrm{}\pm 0.03){\chi }_M$, where ${\chi }_M$ is the molar susceptibility. The second moments are determined as $M_2=(24\mathrm{}\pm 2)+(45\pm 3)\times {10}^{-4\mathrm{}}{h}^2$ ${\mathrm{Oe}}^2$ in $\beta$-U${\mathrm{H}}_3$, and $M_2=(56.4\mathrm{}\pm 1.5)+(48.5\pm 3)\times {10}^{-4\mathrm{}}{h}^2$ ${\mathrm{Oe}}^2$ in $\beta$-U${\mathrm{D}}_3$, where $h=\frac{H_0}{(T-\theta )}$, $\theta$ being the appropriate paramagnetic Curie temperature. Analysis of the linewidth, line shape, and second moment showed that there are three line-broadening mechanisms (four in the deuteride): internuclear dipolar broadening, the (classical) dipolar field of the $5f$ electrons on the uranium ions, and an effect due to the use of powder samples (in the deuteride, a quadrupolar interaction is also present, with $\left|\frac{e^2\mathrm{qQ}}{h}\right|=14.5\mathrm{}\pm 0.5$ kHz). The line shapes, due to the simultaneous presence of several broadening mechanisms, are discussed in some detail. The $5f$ electrons are shown to be localized and do not form a band. The ferromagnetic interaction was analyzed using a simple Ruderman-Kittel-Kasuya-Yosida model, from which it is deduced that the coupling constant $\Gamma \sim 20$ eV ${\mathrm{\AA }}^3$,