Abstract
THE mechanism of superconductivity in alkali-metal compounds of C6o (refs 1, 2) remains controversial. Electron-pairing mechanisms based on electron-phonon coupling involving both low-frequency (intermolecular) vibrations3 and high-frequency (intramolecular) modes4,5—the strong-coupling and weak-coupling cases respectively—have been proposed. These two mechanisms have different associated energy scales, which is reflected in the magnitude of the superconducting energy gap. Measurements of the gap for these compounds have been reported previously for powder samples6–8, but are somewhat discrepant or ambiguous, perhaps owing to grain-size or grain-junction effects. Here we report measurements on large single-crystal samples of K3C60 and Rb3C60 using optical reflectivity. We obtain values for the reduced gap ratio, 2Δ/k8Tc of 3.44 and 3.45 respectively, consistent with predictions for a mechanism based on standard Bardeen-Cooper-Schrieffer (BCS) electron-phonon coupling to intramolecular modes.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Hebard, A. F. et al. Nature 350, 600–601 (1991).
Holczer, K. et al. Science 252, 1154–1157 (1991).
Zhang, F. C., Ogata, M. & Rice, T. M., Phys. Rev. Lett. 67, 3452–3455 (1991).
Varma, C. M., Zaanen, J. & Raghavachari, K. Science 254, 989–992 (1991).
Schluter, M., Lannoo, M., Needels, M., Baraff, G. A. & Tomanek D. Phys. Rev. Lett 68, 526–529 (1992).
Zhang, Z., Chen, C.-C., Kelty, S. P., Dai, H. & Lieber, C.M. Nature 353, 333–335 (1991).
Kiefl, R. F. et al. Phys. Rev. Lett. 70, 3987–3990 (1993).
Degiorgi, L. et al. Phys. Rev. B49, 7012–7025 (1994).
Xiang, X. D. et al. Science 256, 1190–1191 (1992).
Xiang, S. D., Hou, J. G., Crespi, V. H., Zettl, A. & Cohen, M. L. Nature 361, 54–56 (1993).
Martin, M. C., Koller, D. & Mihaly, L. Phys. Rev. B47, 14607–14610 (1993).
Iwasa, Y., Yasuda, T., Koda, T. & Koda, S. Phys. Rev. Lett 69, 2284–2287 (1992).
Bonn, D. A. et al. Phys. Rev. B35, 8843–8845 (1987).
Mattis, D. C. & Bardeen, J. Phys. Rev. 111, 412–417 (1958).
Ramirez, A. P. et al. Phys. Rev. Lett. 68, 1058–1060 (1992).
Ramirez, A. P., Rosseinsky, M. J., Murphy, D. W. & Haddon, R. C. Phys. Rev. Lett. 69, 1687–1690 (1992).
Quirion, G. et al. Europhys. Lett. 21, 233–238 (1993).
Rotter, L. D. et al. Nature 355, 532–534 (1992).
Fitzgerald, S. A., Kaplan, S. C., Rosenberg, A., Sievers, A. J. & McMordie, R. A. S. Phys. Rev B45, 10165–10168 (1992).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Degiorgi, L., Briceno, G., Fuhrer, M. et al. Optical measurements of the superconducting gap in single-crystal K3C60 and Rb3C60. Nature 369, 541–543 (1994). https://doi.org/10.1038/369541a0
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/369541a0
This article is cited by
-
Tuning the electronic states and superconductivity in alkali fulleride films
AAPPS Bulletin (2022)
-
Pressure tuning of light-induced superconductivity in K3C60
Nature Physics (2018)
-
Possible light-induced superconductivity in K3C60 at high temperature
Nature (2016)
-
Interpretation of anomalous normal state optical conductivity of K 3 C 60 fullerides
Bulletin of Materials Science (2013)
-
Optical spectroscopy on alkali-metal doped fullerene compounds
Journal of Low Temperature Physics (1996)
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.
