Large energy gaps in CaC6 from tunneling spectroscopy: Possible evidence of strong-coupling superconductivity
Cihan Kurter, Lutfi Ozyuzer, Daniel Mazur, John F. Zasadzinski, Daniel Rosenmann, Helmut Claus, Dave G. Hinks, Kenneth E. Gray
DOI 10.1103/PhysRevB.76.220502 · Physical Review B
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Abstract
Tunneling in CaC6 crystals reproducibly reveals superconducting gaps Δ of 2.3±0.2meV that are ∼40% larger than reported earlier. In an isotropic s-wave scenario, that puts CaC6 into the class of very strongly coupled superconductors, since 2Δ∕kTc∼4.6, implying that soft Ca phonons are primarily involved in the superconductivity. This conclusion explains the relatively large Ca isotope effect found recently for CaC6, but it could also signal a strong anisotropy in the electron-phonon interaction.
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 unresolved | onset |
| CaC6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 15.1 | 8 GPa | unknown |
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