Europhys. Lett.
Volume 73, Number 6, March 2006
Page(s) 948 - 954
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 15 February 2006
Europhys. Lett., 73 (6), pp. 948-954 (2006)
DOI: 10.1209/epl/i2005-10485-3

Dissipation in ultra-thin current-carrying superconducting bridges; evidence for quantum tunneling of Pearl vortices

F. Tafuri1, J. R. Kirtley2, D. Born3, D. Stornaiuolo3, P. G. Medaglia4, P. Orgiani4, G. Balestrino4 and V. G. Kogan5

1  Dipartimento di Ingegneria dell'Informazione Seconda Università di Napoli Aversa (CE), Italy
2  IBM Watson research center - Route 134 Yorktown Heights, NY 10598, USA
3  CNR-INFM Coherentia, Dipartimento di Scienze Fisiche Università di Napoli "Federico II" - Napoli, Italy
4  CNR-INFM Coherentia, Dipartimento di Ingegneria Meccanica Università di Roma Tor Vergata - Roma, Italy
5  Ames Laboratory-DOE and Department of Physics and Astronomy Iowa State University - Ames, IA 50011-3160, USA

received 8 November 2005; accepted in final form 26 January 2006
published online 15 February 2006

We have made zero-field current-voltage (IV) measurements of artificially layered high-Tc thin-film bridges. SQUID microscopy of these films provides Pearl lengths $\Lambda$ longer than the bridge widths, and shows current distributions that are uniform across the bridges. At high temperatures and high currents the voltages follow the power law $V \propto I^n$, with $n=\Phi_0^2/8\pi^2\Lambda k T+1$, in good agreement with the predictions for thermally activated vortex motion. At low temperatures, the IV's are better fit by $\ln V$ linear in I-2, as expected if the low-temperature dissipation is dominated by quantum tunneling of individual Pearl vortices.

74.25.Qt - Vortex lattices, flux pinning, flux creep.
74.78.Bz - High-Tc films.
74.78.Fk - Multilayers, superlattices, heterostructures.

© EDP Sciences 2006