The electronic structure of Ca-intercalated superconducting graphite CaC6

H. Okazaki, R. Yoshida, K. Iwai, K. Noami, T. Muro, T. Nakamura, Takanori Wakita, Yuji Muraoka, M. Hirai, F. Tomioka, Y. Takano, A. Takenaka, M. Toyoda, T. Oguchi, Takayoshi Yokoya

Research output: Contribution to journalArticle

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Abstract

We have measured Ca-intercalated graphite superconductor CaC6 (Tc = 11.2 K) by soft X-ray photoemission spectroscopy in order to understand the electronic structure. For the valence band, we observed several structures that correspond to those of calculated density of states with the partial density of states of Ca 3d at the Fermi level (EF). We also observed core level spectra that are a very large asymmetric Ca 2p and asymmetric C 1s for CaC6, suggesting the existence of conduction electrons derived from Ca 3d and a charge transfer from Ca to graphene layer. These results provide spectroscopic evidence for PDOS of Ca 3d at EF. From a comparison of electronic structure of CaC6 and other graphite intercalation compounds (GICs), we found the difference between CaC6 and other superconducting GICs, which provides deeper understanding of the superconductivity of CaC6.

Original languageEnglish
Pages (from-to)1041-1044
Number of pages4
JournalPhysica C: Superconductivity and its Applications
Volume469
Issue number15-20
DOIs
Publication statusPublished - Oct 15 2009

Fingerprint

Intercalation compounds
Graphite
Electronic structure
graphite
electronic structure
intercalation
Core levels
Photoelectron spectroscopy
Valence bands
X ray spectroscopy
Superconductivity
Fermi level
Graphene
Superconducting materials
Charge transfer
conduction electrons
Electrons
graphene
photoelectric emission
superconductivity

Keywords

  • Electronic structure
  • Graphite intercalation compounds
  • Soft X-ray photoemission spectroscopy

ASJC Scopus subject areas

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

Cite this

The electronic structure of Ca-intercalated superconducting graphite CaC6 . / Okazaki, H.; Yoshida, R.; Iwai, K.; Noami, K.; Muro, T.; Nakamura, T.; Wakita, Takanori; Muraoka, Yuji; Hirai, M.; Tomioka, F.; Takano, Y.; Takenaka, A.; Toyoda, M.; Oguchi, T.; Yokoya, Takayoshi.

In: Physica C: Superconductivity and its Applications, Vol. 469, No. 15-20, 15.10.2009, p. 1041-1044.

Research output: Contribution to journalArticle

Okazaki, H, Yoshida, R, Iwai, K, Noami, K, Muro, T, Nakamura, T, Wakita, T, Muraoka, Y, Hirai, M, Tomioka, F, Takano, Y, Takenaka, A, Toyoda, M, Oguchi, T & Yokoya, T 2009, 'The electronic structure of Ca-intercalated superconducting graphite CaC6 ', Physica C: Superconductivity and its Applications, vol. 469, no. 15-20, pp. 1041-1044. https://doi.org/10.1016/j.physc.2009.05.172
Okazaki, H. ; Yoshida, R. ; Iwai, K. ; Noami, K. ; Muro, T. ; Nakamura, T. ; Wakita, Takanori ; Muraoka, Yuji ; Hirai, M. ; Tomioka, F. ; Takano, Y. ; Takenaka, A. ; Toyoda, M. ; Oguchi, T. ; Yokoya, Takayoshi. / The electronic structure of Ca-intercalated superconducting graphite CaC6 In: Physica C: Superconductivity and its Applications. 2009 ; Vol. 469, No. 15-20. pp. 1041-1044.
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AB - We have measured Ca-intercalated graphite superconductor CaC6 (Tc = 11.2 K) by soft X-ray photoemission spectroscopy in order to understand the electronic structure. For the valence band, we observed several structures that correspond to those of calculated density of states with the partial density of states of Ca 3d at the Fermi level (EF). We also observed core level spectra that are a very large asymmetric Ca 2p and asymmetric C 1s for CaC6, suggesting the existence of conduction electrons derived from Ca 3d and a charge transfer from Ca to graphene layer. These results provide spectroscopic evidence for PDOS of Ca 3d at EF. From a comparison of electronic structure of CaC6 and other graphite intercalation compounds (GICs), we found the difference between CaC6 and other superconducting GICs, which provides deeper understanding of the superconductivity of CaC6.

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