ELECTRONIC INSTABILITY AT HIGH FLUX-FLOW VELOCITIES IN HIGH-T-C SUPERCONDUCTING FILMS

At high flux-flow velocities in type-II superconductors the nonequilib rium distribution of the quasiparticles leads to an electronic instabi lity and an aburpt switching into a state with higher electric resisti vity, as predicted by Larkin and Ovchinnikow (LO). We report the first obervation of this effect in a high-temperature superconductor, namel y in epitaxial c-axis oriented films of YBa(2)Cu3O(7)-(delta). Using t he LO therory, we have extracted from out results the inelastic quasip article scattering rare tau(in)(-1), which strongly decreases with dec reasing temperature below T-c