Electronic structure of La-intercalated graphite

We demonstrate that a graphite-intercalation compound (GIC) with La is formed when an 80-Å-thick film of La metal deposited onto highly oriented pyrolytic graphite is annealed at temperatures between 400 and 1200 °C. The resulting intercalation compound was studied by angle-resolved photoemission, Auger-electron spectroscopy, and low-energy-electron diffraction. It was found that despite differences in the electronic configurations of La metal (d metal) and alkali metals (s metals), the valence-band structure of the obtained La-GIC is quite similar to that of alkali-GIC. It is proposed that the electronic structure of the La-GIC can be described in first approximation by a rigid-band model, where the valence electrons of La are preferentially transferred to the graphite ${\mathit{p}}_{\mathrm{\pi }}^{\mathrm{*}}$ band and not so much to states of the three-dimensional interlayer band.