POSITRON-ANNIHILATION STUDY OF THE ELECTRONIC-STRUCTURE OF LAB6

We measured the two-dimensional angular correlation of the positron an nihilation radiation (2D-ACAR) on a single crystal of LaB6 for two pro jections, The anisotropies of the 2D electron-positron momentum densit y were very similar to those previously observed for the isostructural heavy-fermion (HF) system CeB6 in the paramagnetic phase and consiste nt with those of the calculated electron-positron momentum density of LaB6. The standard LCW analysis was in reasonable agreement with calcu lations of the LCW-folded 2D-ACAR spectrum and de Haas van Alphen (dHv A) findings. From the projected k-space density we could evaluate the Fermi volume, corresponding to 1.10 +/- 0.04 electrons per formula uni t, and deduce that the effect of the non-uniform positron density does not play a significant role.