Interlayer-state-driven superconductivity in CaC6 studied by angle-resolved photoemission spectroscopy

Wonshik Kyung, Yeongkwan Kim, Garam Han, Choonshik Leem, Chul Kim, Yoonyoung Koh, Beomyoung Kim, Youngwook Kim, Jun Sung Kim, Keun Su Kim, Eli Rotenberg, Jonathan D. Denlinger, Changyoung Kim

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Abstract

We performed angle-resolved photoemission experiments on CaC6 and measured kz-dependent electronic structures to investigate the interlayer states. The results reveal a spherical interlayer Fermi surface centered at the Γ point. We also find that the graphene-driven band possesses a weak kz dispersion. The overall electronic structure shows a peculiar single-graphene-layer periodicity in the kz direction although the CaC6 unit cell is supposed to contain three graphene layers. This suggests that the c-axis ordering of Ca has little effect on the electronic structure of CaC6. In addition to CaC6, we also studied the a low-temperature superconductor BaC6. For BaC6, the graphene-band Dirac-point energy is smaller than that of CaC6. Based on data from CaC6 and BaC6, we rule out the Cxy phonon mode as the origin of the superconductivity in CaC6, which strongly suggests interlayer-state-driven superconductivity.

Original languageEnglish
Article number224516
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume92
Issue number22
DOIs
Publication statusPublished - 2015 Dec 30

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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    Kyung, W., Kim, Y., Han, G., Leem, C., Kim, C., Koh, Y., Kim, B., Kim, Y., Kim, J. S., Kim, K. S., Rotenberg, E., Denlinger, J. D., & Kim, C. (2015). Interlayer-state-driven superconductivity in CaC6 studied by angle-resolved photoemission spectroscopy. Physical Review B - Condensed Matter and Materials Physics, 92(22), [224516]. https://doi.org/10.1103/PhysRevB.92.224516