TY - JOUR AU - Beck, M. AU - Rousseau, I. AU - Klammer, M. AU - Leiderer, P. AU - Mittendorff, M. AU - Winnerl, S. AU - Helm, M. AU - Gol'tsman, G. N. AU - Demsar, J. PY - 2013 DA - 2013// TI - Transient increase of the energy gap of superconducting NbN thin films excited by resonant narrow-band terahertz pulses T2 - Phys. Rev. Lett. JO - Phys. Rev. Lett. SP - 267003 (1 to 5) VL - 110 IS - 26 KW - NbN thin films KW - 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. SN - 0031-9007 UR - http://www.ncbi.nlm.nih.gov/pubmed/23848912 UR - https://doi.org/10.1103/PhysRevLett.110.267003 DO - 10.1103/PhysRevLett.110.267003 N1 - PMID:23848912 ID - Beck_etal2013 ER -