ARPES on Na$_{0.6}$CoO$_{2}$: Fermi surface, extended flat dispersion, and unusual band splitting

H. -B. Yang; S. -C. Wang; A. K. P. Sekharan; H. Matsui; S. Souma; T. Sato; T. Takahashi; T. Takeuchi; J. C. Campuzano; R. Jin; B. C. Sales; D. Mandrus; Z. Wang; H. Ding

doi:10.1103/PhysRevLett.92.246403

paper

ARPES on Na $_{0.6}$ CoO $_{2}$ : Fermi surface, extended flat dispersion, and unusual band splitting

arXiv:cond-mat/0310532 · doi:10.1103/PhysRevLett.92.246403

Abstract

The electronic structure of single crystals Na $_{0.6}$ CoO $_{2}$ , which are closely related to the superconducting Na $_{0.3}$ CoO $_{2}$ . $y$ H $_{2}$ O ( $T_{c} \sim 5 K$ ), 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 ( $I^$ - $K$ , $I^$ - $M$ ). Our ARPES result also indicates that an extended flat band is formed slightly above $E_{F}$ along $I^$ - $K$ . In addition, an unusual band splitting is observed in the vicinity of the Fermi surface along the $I^$ - $M$ direction, which differs from the predicted bilayer splitting.

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ARPES on Na0.6​CoO2​: Fermi surface, extended flat dispersion, and unusual band splitting

Abstract

ARPES on Na $_{0.6}$ CoO $_{2}$ : Fermi surface, extended flat dispersion, and unusual band splitting