Low-energy excitations and Fermi surface topology of parent cobaltate superconductor

M. Z. Hasan, D. Qian, M. Foo, R. J. Cava

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


The essential framework for cuprate superconductivity is that of a spin-1/2 electron system in the vicinity of a half filled (Mott limit) lattice. Of all oxide superconductors, this framework is most closely matched in the sodium doped cobalt oxides except that it is realized on a triangular lattice. We employ angle-resolved photoemission spectroscopy to study the quasiparticle dynamics of the parent cobaltate superconductor. Results reveal a single hole-like Fermi surface generated by the crossing of heavy (∼15 me ∼ 3mLDA) quasiparticles with a negative effective hopping (teff < 0). The observed ground state as given by the topology of the Fermi surface is found be very close to a collective charge instability with sqrt(3) × sqrt(3) symmetry. The measured electron dynamic parameters reveal the unusual character of the parent cobaltate class likely due to small and almost isotropic Fermi velocity (vF (over(k, →)) ∼ vF ∼ 0.4 ± 0.1 eV Å) observed. ARPES data is consistent with bulk thermodynamic specific heat and quantum oscillation measurements.

Original languageEnglish (US)
Pages (from-to)186-189
Number of pages4
JournalPhysica C: Superconductivity and its applications
Volume460-462 I
Issue numberSPEC. ISS.
StatePublished - Sep 1 2007

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


  • Doped Mott insulators
  • Photoemission spectroscopy
  • Sodium cobaltates
  • Superconductivity


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