Observation of gapped quasiparticles in sodium charge-ordered Na1/2CoO2

Y. Xia, D. Qian, D. Hsieh, L. Wray, L. Viciu, R. J. Cava, M. Z. Hasan

Research output: Contribution to journalArticlepeer-review


Using high-resolution photoemission spectroscopy (ARPES), we present a systematic study of the insulating cobaltates. A single-particle gap opening suggests that due to the material's unique topology an anisotropic particle-hole instability is present. Unlike conventional density waves, charge stripes or band insulators, the onset of the gap depends on the quasiparticle's quantum coherence which occurs well below the symmetry-breaking temperature of the crystal. Results are found to be in good agreement with bulk resistivity, specific heat and optical measurements.

Original languageEnglish (US)
Pages (from-to)1007-1009
Number of pages3
JournalPhysica B: Condensed Matter
Issue number5-9
StatePublished - Apr 1 2008

All Science Journal Classification (ASJC) codes

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


  • Frustrated systems
  • Metal-insulator transition
  • Mott insulator
  • Sodium cobaltate
  • Triangular lattice


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