Optical and Photoelectrical Studies of Electronic Structure of R_3Au_3Sb_4 (R=La, Ce and Pr)

Abstract

The electronic structures of a magnetic semiconductorCe₃Au₃Sb₄ and the related materials, La₃Au₃Sb₄ andPr₃Au₃Sb₄, have been investigated by reflectivity andresonant photoemission spectra. From the resonant photoemissionspectra of Ce₃Au₃Sb₄, the hybridization between the Ce4fstate and the Sb5p valence band was found to be weak. This result isconsistent with the electronic structure which is derived from theanalysis of the optical data about the energy gap. The experimentallydetermined electronic structure is compared with a band calculation ofLa₃Au₃Sb₄. The unoccupied 4f state is concluded to be about3 eV above the Fermi level, which is higher by 2 eV than the resultof the band calculation. The exciton like absorption due to thetransition from 4f to 5d states was observed. The intra-atomic Coulombinteraction between 4f and 5d states is thought to play an importantrole.