title: Complete d-band dispersion relation in sodium cobaltates.
abstract: We utilize fine-tuned polarization selection coupled with excitation-energy variation of photoelectron signal to image the complete d-band dispersion relation in sodium cobaltates. A hybridization gap anticrossing is observed along the Brillouin zone corner and the full quasiparticle band is found to emerge as a many-body entity lacking a pure orbital polarization. At low dopings, the quasiparticle bandwidth (Fermion scale, many-body E(F) approximately 0.25 eV) is found to be smaller than most known oxide metals. The low-lying density of states is found to be in agreement with bulk-sensitive thermodynamic measurements for nonmagnetic dopings where the 2D Luttinger theorem is also observed to be satisfied.
authors.affiliation: Department of Physics, Joseph Henry Laboratories, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: D
authors.initials: D
authors.lastname: Qian
authors.forename: L
authors.initials: L
authors.lastname: Wray
authors.forename: D
authors.initials: D
authors.lastname: Hsieh
authors.forename: L
authors.initials: L
authors.lastname: Viciu
authors.forename: R J
authors.initials: RJ
authors.lastname: Cava
authors.forename: J L
authors.initials: JL
authors.lastname: Luo
authors.forename: D
authors.initials: D
authors.lastname: Wu
authors.forename: N L
authors.initials: NL
authors.lastname: Wang
authors.forename: M Z
authors.initials: MZ
authors.lastname: Hasan