ELECTRONIC-STRUCTURE OF HEXAGONAL AL5CO2

We have investigated the electronic structure of hexagonal Al5Co2 thro ugh theoretical as well as experimental means. Two different calculati ons have been carried out within the LMTO and tight-binding-LMTO metho ds. The experimental procedure involved soft-x-ray spectroscopy comple mented by photoemission measurements. Co states have been found near t he Fermi level, in interaction with Al states of hybridized p, s-d cha racter. As a result, a pseudo-gap is generated at the Fermi level. Occ upied Al states beyond 5 eV form the Fermi level are found to be almos t pure s in character. The comparison between the experimental results and calculations indicates a rather good agreement with results from LMTO, consistent with the fact that this is a more elaborate band stru cture calculation. Agreement is only acceptable with results from the TB-LMTO calculations but these can be improved with a more careful tre atment of the TB structure constants.