Abstract
Long-range order is destroyed in a superconductor warmed above its critical temperature (Tc). However, amplitude fluctuations of the superconducting order parameter survive1 and lead to a number of well-established phenomena, such as paraconductivity2: an excess of charge conductivity due to the presence of short-lived Cooper pairs in the normal state. According to theory3, these pairs generate a transverse thermoelectric (Nernst) signal. In two dimensions, the magnitude of the expected signal depends only on universal constants and the superconducting coherence length, so the theory can be rigorously tested. Here, we present measurements of amorphous superconducting films of Nb0.15Si0.85. In this dirty superconductor, the lifetime of Cooper pairs exceeds the elastic scattering lifetime of quasiparticles in a wide temperature range above Tc and, consequently, their Nernst response dominates that generated by the normal electrons. We resolved a Nernst signal, which persists deep inside the normal state. Its amplitude is in excellent agreement with the theoretical prediction. This result provides an unambiguous case for a Nernst effect produced by short-lived Cooper pairs.
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References
Larkin, A. & Varlamov, A. Theory of Fluctuations in Superconductors (Clarendon, Oxford, 2005).
Glover, R. E. Ideal resistive transition of a superconductor. Phys. Lett. A 25, 542–544 (1967).
Ussishkin, I., Sondhi, S. L. & Huse, D. A. Gaussian superconducting fluctuations, thermal transport, and the Nernst effect. Phys. Rev. Lett. 89, 287001 (2002).
Xu, Z. A. et al. Vortex-like excitations and the onset of superconducting phase fluctuation in underdoped La2−xSrxCuO4 . Nature 406, 486–488 (2000).
Wang, Y. et al. Onset of the vortex-like Nernst signal above Tc in La2−xSrxCuO4 and Bi2Sr2−yLayCuO6 . Phys. Rev. B 64, 224519 (2001).
Wang, Y. et al. Dependence of upper critical field and pairing strength on doping in cuprates. Science 299, 86–89 (2003).
Capan, C. et al. Entropy of vortex cores near the superconductor-insulator transition in an underdoped cuprate. Phys. Rev. Lett. 88, 056601 (2002).
Wen, H. H. et al. Two-dimensional feature of the Nernst effect in normal state of underdoped La2−xSrxCuO4 single crystals. Europhys. Lett. 63, 583–589 (2003).
Rullier-Albenque, F. et al. Nernst effect and disorder in the normal state of high-Tc cuprates. Phys. Rev. Lett. 96, 067002 (2006).
Wang, Y., Li, L. & Ong, N. P. Nernst effect in high-Tc superconductors. Phys. Rev. B 73, 024510 (2006).
Schwab, K., Henriksen, E. A., Worlock, J. M. & Roukes, M. L. Measurement of the quantum of thermal conductance. Nature 404, 974–977 (2000).
Dumoulin, L., Bergé, L., Lesueur, J., Bernas, H. & Chapellier, M. Nb-Si thin films as thermometers for low temperature bolometers. J. Low Temp. Phys. 93, 301–306 (1993).
Marnieros, S., Bergé, L., Juillard, A. & Dumoulin, L. Dynamical properties near the metal-insulator transition: evidence for electron-assisted variable range hopping. Phys. Rev. Lett. 84, 2469–2472 (2000).
Lee, H.-L., Carini, J. P., Baxter, D. V., Henderson, W. & Grüner, G. Quantum-critical conductivity scaling for a metal-insulator transition. Science 287, 633–636 (2000).
Goldman, A. M. & Markovic, N. Superconductor–insulator transitions in the two-dimensional limit. Phys. Today 51, 39–44 (1998).
Aubin, H. et al. Magnetic-field-induced quantum superconductor-insulator transition in Nb0.15Si0.85 . Phys. Rev. B 73, 094521 (2006).
Bel, R., Behnia, K. & Burger, H. Ambipolar Nernst effect in NbSe2 . Phys. Rev. Lett. 91, 066602 (2003).
Gilchrist, J. le G. & Vallier, J.-C. Hall effect in superconducting niobium and alloys. Phys. Rev. B 3, 3878–3886 (1971).
Emery, V. J. & Kivelson, S. A. Importance of phase fluctuations in superconductors with small superfluid density. Nature 374, 434–437 (1995).
Jaeger, H. M., Haviland, D. B., Orr, B. G. & Goldman, A. M. Onset of superconductivity in ultrathin granular metal-films. Phys. Rev. B 40, 182–196 (1989).
Maekawa, S., Ebisawa, H. & Fukuyama, H. Upper critical field in two-dimensional superconductors. J. Phys. Soc. Jpn 52, 1352–1360 (1983).
Clogston, A. M. Upper limit for the critical field in hard superconductors. Phys. Rev. Lett. 9, 266–267 (1962).
Bel, R. et al. Giant Nernst effect in CeCoIn5 . Phys. Rev. Lett. 92, 217002 (2004).
Leupold, H. A. & Boorse, H. A. Superconducting and normal specific heats of a single crystal of niobium. Phys. Rev. 134, A1322–A1328 (1964).
Acknowledgements
This work is partially supported by Agence Nationale de la Recherche. We are grateful to C. Capan, A. Kapitulnik, M. Grilli, D. Huse, S. Kivelson, S. Sondhi and I. Ussishkin for useful discussions.
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C.A.M.-K., L.B. and L.D. prepared the samples. A.P. (assisted by H.A. and K.B.) carried out the measurements. H.A. and K.B. (discussing with A.P. and J.L.) interpreted and analysed the data. K.B. wrote the text.
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Pourret, A., Aubin, H., Lesueur, J. et al. Observation of the Nernst signal generated by fluctuating Cooper pairs. Nature Phys 2, 683–686 (2006). https://doi.org/10.1038/nphys413
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DOI: https://doi.org/10.1038/nphys413
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