Article abstract
Nature Physics 1, 117 - 121 (2005)
doi:10.1038/nphys154
Subject Categories: Condensed-matter physics | Quantum physics
Fate of the Josephson effect in thin-film superconductors
Michael Hermele1, Gil Refael2, Matthew P. A. Fisher2 and Paul M. Goldbart3
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.
- Department of Physics, University of California Santa Barbara, Santa Barbara, California 93106, USA
- Kavli Institute for Theoretical Physics, University of California Santa Barbara, Santa Barbara, California 93106, USA
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
Correspondence to: Michael Hermele1 Present address: Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
Correspondence to: Michael Hermele1 e-mail: hermele@mit.edu
Correspondence to: Gil Refael2 Present address: Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
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