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Phys. Rev. B 72, 125125 (2005) [8 pages]

Angle-resolved photoemission spectroscopy of the metallic sodium tungsten bronzes NaxWO3

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S. Raj*, D. Hashimoto, H. Matsui, S. Souma, T. Sato, and T. Takahashi
Department of Physics, Tohoku University, Sendai 980-8578, Japan

Sugata Ray, A. Chakraborty, and D. D. Sarma
Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012, India

Priya Mahadevan
Department of Physics, Indian Institute of Technology, Chennai 600 036, India

W. H. McCarroll
Department of Chemistry and Biochemistry, Rider University, Lawrenceville, New Jersey 08648, USA

M. Greenblatt
Department of Chemistry and Chemical Biology, The State University of New Jersey, Piscataway, New Jersey 08854, USA

Received 17 May 2005; revised 19 July 2005; published 28 September 2005

We have carried out high-resolution angle-resolved photoemission spectroscopy (ARPES) to study the electronic structure of highly metallic NaxWO3 (x=0.58, 0.65, 0.7, and 0.8). The experimentally determined valence-band structure has been compared with the results of an ab initio band-structure calculation. While the presence of an impurity band (level) induced by Na doping is often invoked to explain the insulating state found at low concentrations, we find no signature of impurity band (level) in the metallic regime. The states near EF are populated and the Fermi edge shifts rigidly with increasing electron doping (x). The linear dispersion of the conduction band explains the linear variation of thermodynamic properties including the specific heat and magnetic susceptibility. The presence of an electron-like Fermi surface at Γ(X) and its evolution with increasing Na content and the rigid shift of the Fermi level with increasing x agrees well with the band calculation.

© 2005 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevB.72.125125
DOI:
10.1103/PhysRevB.72.125125
PACS:
79.60.−i, 71.30.+h, 71.18.+y

*Corresponding author. Electronic address: raj@arpes.phys.tohoku.ac.jp

Also at Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 054, India.