Abstract
Observations of radiation-enhanced superconductivity have thus far been limited to a few type-I superconductors (Al, Sn) excited at frequencies between the inelastic scattering rate and the superconducting gap frequency . Utilizing intense, narrow-band, picosecond, terahertz pulses, tuned to just below and above of a BCS superconductor NbN, we demonstrate that the superconducting gap can be transiently increased also in a type-II dirty-limit superconductor. The effect is particularly pronounced at higher temperatures and is attributed to radiation induced nonthermal electron distribution persisting on a 100 ps time scale.
- Received 21 September 2012
DOI:https://doi.org/10.1103/PhysRevLett.110.267003
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