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

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3 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)80-83
Number of pages4
JournalPhysica C: Superconductivity and its applications
Volume460-462 I
Issue numberSPEC. ISS.
Publication statusPublished - Sept 1 2007


  • 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


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