Exploring the dynamics of superconductors by time-resolved far-infrared spectroscopy.
We have examined the recombination of excess quasiparticles in superconducting Pb by time-resolved far-infrared spectroscopy using a pulsed synchrotron source. The energy gap shift calculated by Owen and Scalapino [Phys. Rev. Lett. 28, 1559 (1972)] is directly observed, as is the associated reduction in the Cooper pair density. The relaxation process involves a two-component decay; the faster ( approximately 200 ps) is associated with the actual (effective) recombination process, while the slower ( approximately 10 to 100 ns) is due to heat transport across the film/substrate interface. The temperature dependence of the recombination process between 0. 5T(c) and 0.85T(c) is in good agreement with theory.
Carr
G L
GL
National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973, USA. carr@bnl.gov
Lobo
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LaVeigne
J
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Reitze
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Tanner
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