  We studied the high driving force regime of the current-voltage transport
response in the mixed state of amorphous molybdenum-germanium superconducting
films to the point where the flux flow becomes unstable. The observed nonlinear
response conforms with the classic Larkin-Ovchinikov (LO) picture with a
quasiparticle-energy-relaxation rate dominated by the quasiparticle
recombination process. The measured energy relaxation rate was found to have a
magnitude and temperature dependence in agreement with theory.
  PACS: 74.40.Gh, 74.25.Uv, 72.15.Lh, 73.50.Gr, 73.50.Fq
  Keywords: fluxon, vortices, TDGL, FFF, negative differential conductivity,
NDC, non-monotonic IV curve
