Progress in Superconductivity

The Korean Superconductivity Society (한국초전도학회)
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Anisotropic Superconducting Gap of Alkaline-earth Intercalated Graphites: $CaC_6$ and $SrC_6$

알칼리토류 금속이 층간삽입된 흑연의 초전도갭 이방성

  • Kim, Young-Wook (Department of Physics, Pohang University of Science and Technology) ;
  • Kremer, Reinhard K. (Max-Planck-Institut fuer Festkoerperforschung) ;
  • Kim, Jun-Sung (Department of Physics, Pohang University of Science and Technology)
  • Received : 2011.03.03
  • Accepted : 2011.04.04
  • Published : 2011.04.30
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Abstract

We have investigated the anisotropy of the superconducting properties for $CaC_6$ and $SrC_6$ using upper critical fields ($H_{c2}$) and specific heat ($C_p$). From the upper critical fields of $CaC_6$ at different magnetic field orientations, H//c and H// ab, the anisotropy is found to be ~ 5 at low temperatures, much larger than that of $SrC_6$. These results are in contrast to the stronger anisotropy in the electronic structure for $SrC_6$ than for $CaC_6$ indicating a stronger anisotropy in the superconducting gap in $CaC_6$. The findings are confirmed by the temperature dependence of the superconducting specific heat below $T_c$ for $CaC_6$ and $SrC_6$, suggesting the important role of anisotropic electron-phonon coupling in superconducting intercalated graphites.

Keywords

References

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