ELECTRONIC-STRUCTURE OF EU-GRAPHITE AND YB-GRAPHITE INTERCALATION COMPOUNDS

Angle-resolved photoemission (PE) and AES studies are performed on gra phite intercalation compounds (GIC's) with Eu and Yb prepared ''in sit u'' by the deposition of pure metals onto single-crystalline graphite (0001) surfaces with subsequent annealing at the temperatures of 700 K and 600 K, respectively, The electron structure of Eu-and Yb-GIC's is characterized mainly by graphite-derived bands with corresponding dis persion shifted toward higher binding energy. An additional sharp feat ure obtained with PE close to the Fermi level in the region of the K p oint in the Brillouin zone is assigned to the pi(0) states of graphit e which are filled in GIC's due to the charge transfer from rare-earth atoms. The AES results support the assignment of the above Fermi-ener gy feature to the p-symmetry states of carbon and reveal the ionic-lik e character of chemical bonding in the intercalation compounds based o n the Eu and Yb.