Abstract
It is well known that any weak attractive electron–electron interaction in metals can in principle cause the formation of Cooper pairs, which then condense into a superconducting ground state1. In conventional superconductors, this attractive interaction is mediated by lattice vibrations (phonons). But for the heavy-fermion and high-temperature superconductors, alternative pairing interactions are considered to be possible2. For example, the low-temperature properties of heavy-fermion systems are dominated by antiferromagnetic spin fluctuations, which have been considered theoretically3 as a possible cause for Cooper-pair formation. This picture recently received some experimental support: the resistivity behaviour under pressure of two cerium-based heavy-fermion compounds was shown to be consistent with a magnetically mediated pairing mechanism4. Here we use tunnelling spectroscopy to investigate the superconducting order parameter of a uranium-based heavy-fermion superconductor—epitaxial thin films of UPd2 Al3. Our observation of a strong-coupling feature in the tunnelling conductivity, combined with recent inelastic neutron scattering data13,14,15 strongly suggest a pairing interaction mediated by spin fluctuations.
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
Tinkham, M. Introduction to Superconductivity (McGraw-Hill, New York, (1996)).
Cox, D. L. & Maple, M. B. Electronic pairing in exotic superconductors. Phys. Today 275, 32–40 (1995).
Miyake, K., Schmitt-Rink, S. & Varma, C. M. Spin-fluctuation-mediated even-parity pairing in heavy-fermion superconductors. Phys. Rev. B 34, 6554–6556 (1986).
Mathur, N. D.et al. Magnetically mediated superconductivity in heavy fermion compounds. Nature 394, 39–43 (1998).
Grewe, N. & Steglich, F. in Handbook on the Physics and Chemistry of Rare Earth (eds Gscheidner, K. A. & Eyring, L.) Vol. 14, Ch. 97 (Elsevier Science, Amsterdam, (1991)).
Gloos, K.et al. Scaling behaviour of point contacts between a tungsten tip and the heavy-fermion superconductors. J. Low. Temp. Phys. 105, 37–65 (1996).
von Loehneysen, H. Probing the energy gap of the heavy-fermion superconductors. Physica B 218, 148–156 (1996).
Geibel, C.et al. Heavy-fermion superconductivity at Tc = 2 K in the antiferromagnet UPd2 Al3. Z. Phys. B 84, 1–2 (1991).
Huth, M., Kaldowski, A., Hessert, J., Heske, C. & Adrian, H. UPd2 Al3 heavy fermion superconducting films. Physica B 199 & 200, 116–118 (1994).
Hiess, A.et al. Magnetic properties of UPd2 Al3 thin films investigated by resonant magnetic x-ray scattering. Physica B (in the press).
Dynes, R. C., Narayanamurti, V. & Garno, J. Direct measurement of quasiparticle-lifetime broadening in a strong-coupled superconductor. Phys. Rev. Lett. 41, 1509–1512 (1978).
Caspary, R.et al. Unusual ground state properties of UPd2 Al3 : Implications for the co-existence of heavy-fermion-superconductivity and local-moment antiferromagnetism. Phys. Rev. Lett. 71, 2146–2149 (1993).
Sato, N.et al. Spin fluctuations in the heavy fermion superconductor UPd2 Al3 studied by neutron inelastic scattering. J. Phys. Soc. Jpn 66, 1884–1887 (1997).
Metoki, N., Haga, Y., Koike, Y. & Onuki, Y. Superconducting energy gap observed in the magnetic excitation spectra of a heavy fermion superconductor UPd2 Al3. Phys. Rev. Lett. 80, 5417–5420 (1998).
Bernhoeft, N.et al. Magnetic fluctuations above and below Tc in the heavy fermion superconductor UPd2 Al3. Physica B (in the press).
Parks, R. D. in SuperconductivityCh. 10 (Marcel Dekker, New York, (1969)).
Millis, A. J., Sachdev, S. & Varma, C. M. Inelastic scattering and pair breaking in anisotropic and isotropic superconductors. Phys. Rev. B 37, 4975–4986 (1988).
Tou, H.et al. D-wave superconductivity in antiferromagnetic heavy-fermion compound UPd2 Al3 —evidence from 27A1 NMR/NQR studies. J. Phys. Soc. Jpn 64, 725–729 (1995).
Matsuda, K., Kohori, Y. & Kohara, T. Observation of 105Pd NMR and NQR signals in the heavy-fermion superconductor UPd2 Al3. Phys. Rev. B 55, 15223–15227 (1997).
Hiroi, M.et al. Thermal conductivity of a heavy fermion superconductor UPd2 Al3 single crystal. J. Phys. Soc. Jpn 66, 1595–1598 (1997).
Yip, S. & Garg, A. Superconducting states of reduced symmetry: General order parameters and physical implications. Phys. Rev. B 48, 3304–3308 (1993).
Hessert, J.et al. Temperature and angular dependence of the upper critical field of UPd2 Al3 thin films. Physica B 230–232, 373–376 (1997).
Acknowledgements
We thank P. Haibach for experimental support. This work was supported by the Deutsche Forschungsgemeinschaft.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Jourdan, M., Huth, M. & Adrian, H. Superconductivity mediated by spin fluctuations in the heavy-fermion compound UPd2 Al3. Nature 398, 47–49 (1999). https://doi.org/10.1038/17977
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/17977
This article is cited by
-
Quantum-well states at the surface of a heavy-fermion superconductor
Nature (2023)
-
Extremely slow Drude relaxation of correlated electrons
Nature (2005)
-
Submillimeter spectroscopy of materials with correlated electrons
Radiophysics and Quantum Electronics (2005)
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.
