The electronic structure of Ca-intercalated superconducting graphite CaC6

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

doi:10.1016/j.physc.2009.05.172

The electronic structure of Ca-intercalated superconducting graphite CaC₆

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

Research output: Contribution to journal › Article › peer-review

3 Citations (Scopus)

Abstract

We have measured Ca-intercalated graphite superconductor CaC₆ (T_c = 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 (E_F). 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 E_F. 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 language	English
Pages (from-to)	1041-1044
Number of pages	4
Journal	Physica C: Superconductivity and its applications
Volume	469
Issue number	15-20
DOIs	https://doi.org/10.1016/j.physc.2009.05.172
Publication status	Published - Oct 15 2009

Keywords

Electronic structure
Graphite intercalation compounds
Soft X-ray photoemission spectroscopy

ASJC Scopus subject areas

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

Access to Document

10.1016/j.physc.2009.05.172

Cite this

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, 469(15-20), 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, 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

@article{0194e55286ac4c68a5ab02b12ae04117,

title = "The electronic structure of Ca-intercalated superconducting graphite CaC6",

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.",

keywords = "Electronic structure, Graphite intercalation compounds, Soft X-ray photoemission spectroscopy",

author = "H. Okazaki and R. Yoshida and K. Iwai and K. Noami and T. Muro and T. Nakamura and T. Wakita and Y. Muraoka and M. Hirai and F. Tomioka and Y. Takano and A. Takenaka and M. Toyoda and T. Oguchi and T. Yokoya",

note = "Funding Information: For sample preparation, we thank Y. Kubozono, Y. Ohta, and N. Kawasaki. We also thank K. Okada for valuable discussions. This work was partially supported by a Grant-in-Aid for Scientific Research of the Ministry of Education, Culture, Sports, Science and Technology, Japan. The SXPES experiments at BL25SU of SPring-8 were performed under a proposal number 2008A1740.",

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T1 - The electronic structure of Ca-intercalated superconducting graphite CaC6

AU - Okazaki, H.

AU - Yoshida, R.

AU - Iwai, K.

AU - Noami, K.

AU - Muro, T.

AU - Nakamura, T.

AU - Wakita, T.

AU - Muraoka, Y.

AU - Hirai, M.

AU - Tomioka, F.

AU - Takano, Y.

AU - Takenaka, A.

AU - Toyoda, M.

AU - Oguchi, T.

AU - Yokoya, T.

N1 - Funding Information: For sample preparation, we thank Y. Kubozono, Y. Ohta, and N. Kawasaki. We also thank K. Okada for valuable discussions. This work was partially supported by a Grant-in-Aid for Scientific Research of the Ministry of Education, Culture, Sports, Science and Technology, Japan. The SXPES experiments at BL25SU of SPring-8 were performed under a proposal number 2008A1740.

PY - 2009/10/15

Y1 - 2009/10/15

N2 - 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.

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.

KW - Electronic structure

KW - Graphite intercalation compounds

KW - Soft X-ray photoemission spectroscopy

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