Neutron scattering study of the ferromagnetic superconductorUGe2

Unpolarized and polarized neutron scattering experiments have been performed at ambient pressure on a single crystal of the itinerant electron superconductor ${\mathrm{UGe}}_2$ in both the ferromagnetic and the paramagnetic phases. Unpolarized neutrons have confirmed the ${\mathrm{ZrGa}}_2$-type orthorhombic crystal structure of ${\mathrm{UGe}}_2$ and a ferromagnetic ordering below $T_C=53\mathrm{}\hspace{0.5em}\mathrm{K}$ with the moments aligned along the $a$ axis. No evidence of any modulated component for the magnetic structure has been found. Polarized neutron data have shown a large and almost spherical magnetization distribution at the U sites and no induced moment at the Ge sites. Refinements of the magnetic structure factors within the dipolar approximation allow the magnitude of the orbital and spin uranium moments to be quantified, and a comparison to the measured static magnetization reveals that there is no diffuse contribution.