PT Journal
AU Beck, M
   Rousseau, I
   Klammer, M
   Leiderer, P
   Mittendorff, M
   Winnerl, S
   Helm, M
   Gol'tsman, GN
   Demsar, J
TI Transient increase of the energy gap of superconducting NbN thin films excited by resonant narrow-band terahertz pulses
SO Phys. Rev. Lett.
JI Phys. Rev. Lett.
PY 2013
BP 267003 (1 to 5)
VL 110
IS 26
DI 10.1103/PhysRevLett.110.267003
DE NbN thin films; energy gap
AB 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 2Delta/h. Utilizing intense, narrow-band, picosecond, terahertz pulses, tuned to just below and above 2Delta/h 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.
ER