Positron annihilation study of the electronic structure of LaB6

We measured the two-dimensional angular correlation of the positron annihilation radiation (2D-ACAR) on a single crystal of LaB6 for two projections. The anisotropies of the 2D electron-positron momentum density were very similar to those previously observed for the isostructural heavy-fermion (HF) system CeB6 in the paramagnetic phase and consistent with those of the calculated electron-positron momentum density of LaB6. The standard LCW analysis was in reasonable agreement with calculations of the LCW-folded 2D-ACAR spectrum and de Haas van Alphen (dHvA) findings. From the projected k-space density we could evaluate the Fermi volume, corresponding to 1.10 ± 0.04 electrons per formula unit, and deduce that the effect of the non-uniform positron density does not play a significant role.