Metal-insulator transition of NaxWO3 studied by angle-resolved photoemission spectroscopy

Satyabrata Raj, Takafumi Sato, Seigo Souma, Takashi Takahashi, D. D. Sarma, Priya Mahadevan

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7 Citations (Scopus)


The electronic structure of sodium tungsten bronzes NaxWO 3 is investigated by high-resolution angle-resolved photoemission spectroscopy (ARPES). The ARPES spectra measured in both insulating and metallic phases of NaxWO3 reveals the origin of metal-insulator transition (MIT) in sodium tungsten bronze system. It is found that in insulating NaxWO3 the states near the Fermi level (E F) are localized due to the strong disorder caused by the random distribution of Na+ ions in WO3 lattice. Due to the presence of disorder and long-range Coulomb interaction of conduction electrons, a soft Coulomb gap arises, where the density of states vanishes exactly at EF. In the metallic regime the states near EF are populated and the Fermi level shifts upward rigidly with increasing electron doping (x). Volume of electron-like Fermi surface (FS) at the Γ(X) point of the Brillouin zone gradually increases with increasing Na concentration due to W 5d t2g band filling. A rigid shift of the Fermi energy is found to give a qualitatively good description of the Fermi surface evolution. As we move from bulk-sensitive to more surface sensitive photon energy, we found the emergence of Fermi surfaces at X(M) and M(R) points similar to the one at the Γ(X) point in the metallic regime, suggesting that the reconstruction of surface was due to rotation/deformation of WO6 octahedra.

Original languageEnglish
Pages (from-to)2819-2846
Number of pages28
JournalModern Physics Letters B
Issue number24
Publication statusPublished - 2009 Sep 20


  • Band structure
  • Metal-insulator transition
  • Photoemission spectroscopy
  • Tungsten bronze

ASJC Scopus subject areas

  • Statistical and Nonlinear Physics
  • Condensed Matter Physics


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