Valence Band of Ce2Co0.8Si3.2 and Ce2RhSi3 Studied by Resonant Photoemission Spectroscopy and FPLO Calculations

This work presents studies of the valence band of two Kondo lattice systems: Ce2Co0.8Si3.2, which is paramagnetic with the Kondo temperature T-K approximate to 50 K and Ce2RhSi3, which is antiferromagnetic below T-N = 4.5 K and exhibits TK approximate to 9 K. The photoemission spectra, which are obtained with photon energy tuned to Ce - 4d 4f resonance, reveal a Kondo peak at the Fermi energy (E-F), its spin orbit splitting partner at 0.24 eV and a broad maximum related to Ce f(0) final state. The spectra indicate that Kondo peak has a higher intensity for Ce2Co0.8Si3.2. The off-resonance photoemission data reveal that a maximum in the 3d electron density of states is shifted towards EF for Ce2Co0.8Si3.2 as compared to Ce2RhSi3. Full-potential local-orbital calculations were realized with local spin density approach +U approach for 213 stoichiometry. They show that a higher density of states near EF is observed for Ce2CoSi3. The calculations also reveal the existing tendencies for antiferromagnetic and ferromagnetic ground states in a case of Ce2RhSi3 and Ce2CoSi3, respectively.