Author: ["Michael Hermele","Gil Refael","Matthew P. A. Fisher","Paul M. Goldbart"]
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Abstract
The d.c. Josephson effect refers to the dissipationless electrical current—the supercurrent—that can be sustained across a weak link connecting two bulk superconductors. This effect probes the nature of the superconducting state, which depends crucially on spatial dimensionality. For bulk (that is, three-dimensional) superconductors, the superconductivity is most robust and the Josephson effect is sustained even at non-zero temperature. However, in wires and thin films, thermal and quantum fluctuations play a crucial role. In superconducting wires, these effects qualitatively modify the electrical transport across a weak link. Despite several experiments involving weak links between thin-film superconductors, little theoretical attention has been paid to the electrical conduction in such systems. Here, we analyse the case of two superconducting thin films connected by a point contact. Remarkably, the Josephson effect is absent at non-zero temperature. The point-contact resistance is non-zero and varies with temperature in a nearly activated fashion, with a universal energy barrier set by the superfluid stiffness characterizing the films. This behaviour reflects the subtle nature of thin-film superconductors and should be observable in future experiments.Cite this article
Hermele, M., Refael, G., Fisher, M. et al. Fate of the Josephson effect in thin-film superconductors. Nature Phys 1, 117–121 (2005). https://doi.org/10.1038/nphys154 