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
DOI 10.1103/PhysRevB.92.224516 · Physical Review B
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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.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| CaC6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 11.6 | Pressure not reported | onset |
| BaC6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 0.065 | Pressure not reported | unknown |
| KC8 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 0.39 | Pressure not reported | unknown |
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