The electronic structure of single crystals Na0.6CoO2, which are closely related to the superconducting Na0.3CoO2.yH2O (Tc∼5K), is studied by angle-resolved photoelectron spectroscopy. While the measured Fermi surface is found to be consistent with the prediction of a local density band theory, the energy dispersion is highly renormalized, with an anisotropy along the two principle axes (Γ-K, Γ-M). Our ARPES result also indicates that an extended flat band is formed slightly above EF along Γ-K. In addition, an unusual band splitting is observed in the vicinity of the Fermi surface along the Γ-M direction, which differs from the predicted bilayer splitting.
@article{arxiv.cond-mat/0310532,
title = {ARPES on Na$_{0.6}$CoO$_{2}$: Fermi surface, extended flat dispersion, and unusual band splitting},
author = {H. -B. Yang and S. -C. Wang and A. K. P. Sekharan and H. Matsui and S. Souma and T. Sato and T. Takahashi and T. Takeuchi and J. C. Campuzano and R. Jin and B. C. Sales and D. Mandrus and Z. Wang and H. Ding},
journal= {arXiv preprint arXiv:cond-mat/0310532},
year = {2007}
}