title: Fermi surface evolution and Luttinger theorem in Na(x)CoO2: a systematic photoemission study.
abstract: We report a systematic angle-resolved photoemission study on Na(x)CoO2 for a wide range of Na concentrations (0.3 < or = x < or = 0.72). In all the metallic samples at different x, we observed (i) only a single holelike 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) 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.
authors.affiliation: Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA.
authors.forename: H-B
authors.initials: HB
authors.lastname: Yang
authors.forename: Z-H
authors.initials: ZH
authors.lastname: Pan
authors.forename: A K P
authors.initials: AK
authors.lastname: Sekharan
authors.forename: T
authors.initials: T
authors.lastname: Sato
authors.forename: S
authors.initials: S
authors.lastname: Souma
authors.forename: T
authors.initials: T
authors.lastname: Takahashi
authors.forename: R
authors.initials: R
authors.lastname: Jin
authors.forename: B C
authors.initials: BC
authors.lastname: Sales
authors.forename: D
authors.initials: D
authors.lastname: Mandrus
authors.forename: A V
authors.initials: AV
authors.lastname: Fedorov
authors.forename: Z
authors.initials: Z
authors.lastname: Wang
authors.forename: H
authors.initials: H
authors.lastname: Ding