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Carbon-substitution dependent multiple superconducting gap of MgB$_{2}$: a "sub-meV" resolution photoemission study

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

``Sub-meV'' resolution photoemission spectroscopy was used to study carbon-substitution dependence on the multiple superconducting gap of Mg(B$_{1 - x}$C$_{x})_{2}$. Two features corresponding to $σ$ and $π$ gaps are clearly observed in the raw spectra up to carbon concentration x = 7.5 {%}. The observed x dependence of the two gaps shows a qualitatively different behavior: a marked change of the $σ$ gap proportional to the $T_{c}$ variation and a negligible one of the $π$ gap. This as well as the temperature dependence can be explained with the two-band mean-field theory. Implications from the present study are discussed.

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S. Tsuda, T. Yokoya, T. Kiss, T. Shimojima, S. Shin, T. Togashi, S. Watanabe, C. Chen, S. Lee, H. Uchiyama, S. Tajima, N. Nakai, K. Machida. 2004-09-09. Carbon-substitution dependent multiple superconducting gap of MgB$_{2}$: a "sub-meV" resolution photoemission study. https://doi.org/10.1103/physrevb.72.064527

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