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

Research output: Contribution to journalArticle

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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

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Photoelectron spectroscopy
Superconductivity
Graphene
interlayers
graphene
photoelectric emission
superconductivity
Electronic structure
electronic structure
spectroscopy
Fermi surface
Photoemission
Superconducting materials
Fermi surfaces
periodic variations
cells
Experiments
Temperature
energy

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Kyung, Wonshik ; Kim, Yeongkwan ; Han, Garam ; Leem, Choonshik ; Kim, Chul ; Koh, Yoonyoung ; Kim, Beomyoung ; Kim, Youngwook ; Kim, Jun Sung ; Kim, Keun Su ; Rotenberg, Eli ; Denlinger, Jonathan D. ; Kim, Changyoung. / Interlayer-state-driven superconductivity in CaC6 studied by angle-resolved photoemission spectroscopy. In: Physical Review B - Condensed Matter and Materials Physics. 2015 ; Vol. 92, No. 22.
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Kyung, W, Kim, Y, Han, G, Leem, C, Kim, C, Koh, Y, Kim, B, Kim, Y, Kim, JS, Kim, KS, Rotenberg, E, Denlinger, JD & Kim, C 2015, 'Interlayer-state-driven superconductivity in CaC6 studied by angle-resolved photoemission spectroscopy', Physical Review B - Condensed Matter and Materials Physics, vol. 92, no. 22, 224516. https://doi.org/10.1103/PhysRevB.92.224516

Interlayer-state-driven superconductivity in CaC6 studied by angle-resolved photoemission spectroscopy. / Kyung, Wonshik; Kim, Yeongkwan; Han, Garam; Leem, Choonshik; Kim, Chul; Koh, Yoonyoung; Kim, Beomyoung; Kim, Youngwook; Kim, Jun Sung; Kim, Keun Su; Rotenberg, Eli; Denlinger, Jonathan D.; Kim, Changyoung.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 92, No. 22, 224516, 30.12.2015.

Research output: Contribution to journalArticle

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AU - Kim, Yeongkwan

AU - Han, Garam

AU - Leem, Choonshik

AU - Kim, Chul

AU - Koh, Yoonyoung

AU - Kim, Beomyoung

AU - Kim, Youngwook

AU - Kim, Jun Sung

AU - Kim, Keun Su

AU - Rotenberg, Eli

AU - Denlinger, Jonathan D.

AU - Kim, Changyoung

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N2 - 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.

AB - 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.

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