Sub-meV resolution photoemission study on carbon substituted MgB2

S. Tsuda; T. Yokoya; T. Kiss; T. Shimojima; S. Shin; T. Togashi; S. Watanabe; C. Q. Zhang; C. T. Chen; S. Lee; H. Uchiyama; S. Tajima; N. Nakai; K. Machida

doi:10.1016/j.physc.2007.03.071

Sub-meV resolution photoemission study on carbon substituted MgB₂

S. Tsuda, T. Yokoya, T. Kiss, T. Shimojima, S. Shin, T. Togashi, S. Watanabe, C. Q. Zhang, C. T. Chen, S. Lee, H. Uchiyama, S. Tajima, N. Nakai, K. Machida

School of Science

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

3 Citations (Scopus)

Abstract

We have performed a sub-meV photoemission study on Mg(B_1-xC_x)₂ for x = 0-0.075. The superconducting (SC) transition temperature (T_c) changes systematically from 38 K to 24 K with increasing the carbon concentration. Because of the extremely high-energy resolution of sub-meV, two features corresponding to the two SC gaps originated from π and σ bands are clearly observed even in raw spectra up to x = 0.075. From numerical analyses, we found that the gap size of the σ band is proportional to T_c, while that of the π band is almost constant. The temperature and carbon concentration dependences of the two gaps are explained within a simple two-band model based on a mean field theory. Using the theoretical model, we deduced interband and intraband coupling strength constants. The transition temperature is dominated by the intraband coupling of the σ band, while the interband coupling slightly increases with increasing the carbon concentration. The two-band model shows that the interband coupling slightly pushes up T_c.

Original language	English
Pages (from-to)	80-83
Number of pages	4
Journal	Physica C: Superconductivity and its applications
Volume	460-462 I
Issue number	SPEC. ISS.
DOIs	https://doi.org/10.1016/j.physc.2007.03.071
Publication status	Published - Sept 1 2007

Keywords

Carbon substitution
MgB
Photoemission
Superconducting gap

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.2007.03.071

Cite this

Tsuda, S., Yokoya, T., Kiss, T., Shimojima, T., Shin, S., Togashi, T., Watanabe, S., Zhang, C. Q., Chen, C. T., Lee, S., Uchiyama, H., Tajima, S., Nakai, N., & Machida, K. (2007). Sub-meV resolution photoemission study on carbon substituted MgB₂. Physica C: Superconductivity and its applications, 460-462 I(SPEC. ISS.), 80-83. https://doi.org/10.1016/j.physc.2007.03.071

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title = "Sub-meV resolution photoemission study on carbon substituted MgB2",

abstract = "We have performed a sub-meV photoemission study on Mg(B1-xCx)2 for x = 0-0.075. The superconducting (SC) transition temperature (Tc) changes systematically from 38 K to 24 K with increasing the carbon concentration. Because of the extremely high-energy resolution of sub-meV, two features corresponding to the two SC gaps originated from π and σ bands are clearly observed even in raw spectra up to x = 0.075. From numerical analyses, we found that the gap size of the σ band is proportional to Tc, while that of the π band is almost constant. The temperature and carbon concentration dependences of the two gaps are explained within a simple two-band model based on a mean field theory. Using the theoretical model, we deduced interband and intraband coupling strength constants. The transition temperature is dominated by the intraband coupling of the σ band, while the interband coupling slightly increases with increasing the carbon concentration. The two-band model shows that the interband coupling slightly pushes up Tc.",

keywords = "Carbon substitution, MgB, Photoemission, Superconducting gap",

author = "S. Tsuda and T. Yokoya and T. Kiss and T. Shimojima and S. Shin and T. Togashi and S. Watanabe and Zhang, {C. Q.} and Chen, {C. T.} and S. Lee and H. Uchiyama and S. Tajima and N. Nakai and K. Machida",

note = "Funding Information: This work was supported by Grant-in-aid from the Ministry of Education, Science, and Culture of Japan. This work was supported by the New Energy and Industrial Technology Development Organization (NEDO) as Collaborative Research and Development of Fundamental Technologies for Superconductivity Applications. S.T. thanks JSPS for financial support. We thank Professor A. Chainani for valuable discussions.",

year = "2007",

month = sep,

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doi = "10.1016/j.physc.2007.03.071",

language = "English",

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T1 - Sub-meV resolution photoemission study on carbon substituted MgB2

AU - Tsuda, S.

AU - Yokoya, T.

AU - Kiss, T.

AU - Shimojima, T.

AU - Shin, S.

AU - Togashi, T.

AU - Watanabe, S.

AU - Zhang, C. Q.

AU - Chen, C. T.

AU - Lee, S.

AU - Uchiyama, H.

AU - Tajima, S.

AU - Nakai, N.

AU - Machida, K.

N1 - Funding Information: This work was supported by Grant-in-aid from the Ministry of Education, Science, and Culture of Japan. This work was supported by the New Energy and Industrial Technology Development Organization (NEDO) as Collaborative Research and Development of Fundamental Technologies for Superconductivity Applications. S.T. thanks JSPS for financial support. We thank Professor A. Chainani for valuable discussions.

PY - 2007/9/1

Y1 - 2007/9/1

N2 - We have performed a sub-meV photoemission study on Mg(B1-xCx)2 for x = 0-0.075. The superconducting (SC) transition temperature (Tc) changes systematically from 38 K to 24 K with increasing the carbon concentration. Because of the extremely high-energy resolution of sub-meV, two features corresponding to the two SC gaps originated from π and σ bands are clearly observed even in raw spectra up to x = 0.075. From numerical analyses, we found that the gap size of the σ band is proportional to Tc, while that of the π band is almost constant. The temperature and carbon concentration dependences of the two gaps are explained within a simple two-band model based on a mean field theory. Using the theoretical model, we deduced interband and intraband coupling strength constants. The transition temperature is dominated by the intraband coupling of the σ band, while the interband coupling slightly increases with increasing the carbon concentration. The two-band model shows that the interband coupling slightly pushes up Tc.

AB - We have performed a sub-meV photoemission study on Mg(B1-xCx)2 for x = 0-0.075. The superconducting (SC) transition temperature (Tc) changes systematically from 38 K to 24 K with increasing the carbon concentration. Because of the extremely high-energy resolution of sub-meV, two features corresponding to the two SC gaps originated from π and σ bands are clearly observed even in raw spectra up to x = 0.075. From numerical analyses, we found that the gap size of the σ band is proportional to Tc, while that of the π band is almost constant. The temperature and carbon concentration dependences of the two gaps are explained within a simple two-band model based on a mean field theory. Using the theoretical model, we deduced interband and intraband coupling strength constants. The transition temperature is dominated by the intraband coupling of the σ band, while the interband coupling slightly increases with increasing the carbon concentration. The two-band model shows that the interband coupling slightly pushes up Tc.

KW - Carbon substitution

KW - MgB

KW - Photoemission

KW - Superconducting gap

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