The two-dimensional angular correlation of the positron annihilation radiation on a single crystal of LaB6 was measured for two projections. The anisotropies of the 2D electron-positron momentum density were very similar to those observed for the isostructural heavy-fermion system CeB6 in the paramagnetic phase and consistent with those of the calculated electron-positron momentum density of LaB6. The standard Lock-Crisp-West analysis was in reasonable agreement with the Lock-Crisp-West folding of the calculated two-dimensional angular correlation of the positron annihilation radiation spectrum and the de Haas-van Alphen findings. From the projected k-space density the Fermi volume, corresponding to 1.10±0.04 electrons per formula unit could be evaluated, and it was deduced that the effect of the non-uniform positron density did not play a significant role.

Positron Annihilation Study of the Electronic Structure of LaB6 and CeB6. Biasini, M., Fretwell, H.M., Dugdale, S.B., Alam, M.A., Kubo, Y., Harima, H., Sato, N.: Physical Review B, 1997, 56[16], 10192-9. See also: Applied Surface Science, 1997, 116, 335-9