Fermi surface evolution and Luttinger theorem in Na${}_x$CoO${}_2$: a systematic photoemission study

Abstract

We report a systematic angle-resolved photoemission study on Na${}_x$CoO${}_2$ for a wide range of Na concentrations ($0.3\le x\le 0.72$). In all the metallic samples at different $x$, we observed (i) only a single hole-like Fermi surface centered around $\Gamma$ 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 $e_g^{\prime }$ 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.

4 pages, 5 figures

References in corpus (2)

• Electron correlation and Fermi surface topology of Na${}_x$CoO${}_2$
• The Fermi surface of Na${}_x$CoO${}_2$