POSITRON-ANNIHILATION STUDY OF THE ELECTRONIC-STRUCTURE OF CECU6 AND LACU6

The results of a preliminary study of the electronic structure of the heavy-fermion system CeCu6 via the two-dimensional angular correlation of electron-positron annihilation radiation (2D ACAR) technique were compared with those obtained for the isostructural reference non-f-ele ctron material LaCu6. The spectra relating to the 2 compounds displaye d extremely similar anisotropic structures, with features related to t he symmetry of the Brillouin zone. At present, these structures cannot however be attributed to Fermi-surface or positron wave function effe cts or to anisotropies of some full valence band. In the case of LaCu, , data processing prior to the LCW procedure via new filtering techniq ues revealed a reasonably good agreement between the LCW data and LAPW Fermi-surface calculations while in the case of CeCu6 it appeared dif ficult to relate the results, still of controversial interpretation, t o any theoretical model.