Unstable flux flow due to heated electrons in superconducting films.

A flux instability occurs in superconductors at low temperatures, where e-e scattering is more rapid than e-ph, whereby the dissipation significantly elevates the electronic temperature while maintaining a thermal-like distribution function. The reduction in condensate and rise in resistivity produce a nonmonotonic current-voltage response. In contrast to the Larkin-Ovchinnikov instability where the vortex shrinks, in this scenario the vortex expands and the quasiparticle population rises. Measurements in Y(1)Ba(2)Cu(3)O(7-delta) agree quantitatively with the distinct predictions of this mechanism.