Magnetization density in the intermediate valence compound YbAl3

Polarized neutron diffraction studies have been performed at various temperatures on a flux grown single crystal of YbAl3. Only the Yb carries a field-induced magnetic moment, which is well described by a free in ion Yb3+ form factor. The thermal variation of the localized 4f Yb moment exhibits a second maximum at T approximate to 130 K. A small temperature-independent positive conduction electron polarization is suggested. These results are important to the understanding of the YbAl3 ground state.