We report a systematic angle-resolved photoemission study on NaxCoO2 for a wide range of Na concentrations (0.3≤x≤0.72). In all the metallic samples at different x, we observed (i) only a single holelike Fermi surface centered around Γ and (ii) its area changes with x according to the Luttinger theorem. We also observed a surface state that exhibits a larger Fermi surface area. The eg′ band and the associated small Fermi surface pockets near the K points predicted by band calculations are found to sink below the Fermi energy in a manner almost independent of the doping and temperature.
ASJC Scopus subject areas
- Physics and Astronomy(all)