Optical study of the metal-nonmetal transition in Ni1-δS

H. Okamura, J. Naitoh, T. Nanba, Masanori Matoba, M. Nishioka, S. Anzai, I. Shimoyama, K. Fukui, H. Miura, H. Nakagawa, K. Nakagawa, T. Kinoshita

Research output: Contribution to journalArticle

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Abstract

Optical reflectivity spectra of the hexagonal Ni1-δS have been measured to study its electronic structures, in particular those associated with the metal-nonmetal transition in this compound. Samples with δ approx. 0.002 and 0.02 are studied, which have transition temperatures Tt approx. 260 K and 150 K, respectively. Upon the transition, a pronounced dip appears in the infrared region of the reflectivity spectra. The optical conductivity spectra suggest that the nonmetallic phase is a carrier-doped semiconductor with an energy gap of approx. 0.2-0.3 eV. The spectra also show that the gap becomes larger with decreasing temperature, and smaller with increasing δ. It is found that the overall spectrum in the nonmetallic phase can be explained in terms of a charge-transfer semiconductor, consistent with recent theoretical and photoemission studies of NiS.

Original languageEnglish
Pages (from-to)91-95
Number of pages5
JournalSolid State Communications
Volume112
Issue number2
DOIs
Publication statusPublished - 1999 Sep 6

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Nonmetals
Metals
transition metals
Semiconductor materials
Optical conductivity
Photoemission
Superconducting transition temperature
Electronic structure
Charge transfer
Energy gap
Infrared radiation
reflectance
photoelectric emission
Temperature
transition temperature
charge transfer
electronic structure
conductivity

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

Cite this

Okamura, H., Naitoh, J., Nanba, T., Matoba, M., Nishioka, M., Anzai, S., ... Kinoshita, T. (1999). Optical study of the metal-nonmetal transition in Ni1-δS. Solid State Communications, 112(2), 91-95. https://doi.org/10.1016/S0038-1098(99)00277-X

Optical study of the metal-nonmetal transition in Ni1-δS. / Okamura, H.; Naitoh, J.; Nanba, T.; Matoba, Masanori; Nishioka, M.; Anzai, S.; Shimoyama, I.; Fukui, K.; Miura, H.; Nakagawa, H.; Nakagawa, K.; Kinoshita, T.

In: Solid State Communications, Vol. 112, No. 2, 06.09.1999, p. 91-95.

Research output: Contribution to journalArticle

Okamura, H, Naitoh, J, Nanba, T, Matoba, M, Nishioka, M, Anzai, S, Shimoyama, I, Fukui, K, Miura, H, Nakagawa, H, Nakagawa, K & Kinoshita, T 1999, 'Optical study of the metal-nonmetal transition in Ni1-δS', Solid State Communications, vol. 112, no. 2, pp. 91-95. https://doi.org/10.1016/S0038-1098(99)00277-X
Okamura, H. ; Naitoh, J. ; Nanba, T. ; Matoba, Masanori ; Nishioka, M. ; Anzai, S. ; Shimoyama, I. ; Fukui, K. ; Miura, H. ; Nakagawa, H. ; Nakagawa, K. ; Kinoshita, T. / Optical study of the metal-nonmetal transition in Ni1-δS. In: Solid State Communications. 1999 ; Vol. 112, No. 2. pp. 91-95.
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AU - Nishioka, M.

AU - Anzai, S.

AU - Shimoyama, I.

AU - Fukui, K.

AU - Miura, H.

AU - Nakagawa, H.

AU - Nakagawa, K.

AU - Kinoshita, T.

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AB - Optical reflectivity spectra of the hexagonal Ni1-δS have been measured to study its electronic structures, in particular those associated with the metal-nonmetal transition in this compound. Samples with δ approx. 0.002 and 0.02 are studied, which have transition temperatures Tt approx. 260 K and 150 K, respectively. Upon the transition, a pronounced dip appears in the infrared region of the reflectivity spectra. The optical conductivity spectra suggest that the nonmetallic phase is a carrier-doped semiconductor with an energy gap of approx. 0.2-0.3 eV. The spectra also show that the gap becomes larger with decreasing temperature, and smaller with increasing δ. It is found that the overall spectrum in the nonmetallic phase can be explained in terms of a charge-transfer semiconductor, consistent with recent theoretical and photoemission studies of NiS.

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