EFFECT OF SELF-HEATING ON FLUX FLOW INSTABILITY IN A SUPERCONDUCTOR NEAR T(C)

We have extended the Larkin-Ovchinnikov approach to the problem of viscous flux flow instability in "dirty" superconductors near T(c) by taking into account quasiparticle heating, which is, in principle, unavoidable in finite magnetic fields in the case of real heat removal. According to the relationship between the magnetic field B value and the parameter B(T), introduced by us, there may be two qualitatively different mechanisms of instability: one due to heating of quasiparticles at B >> B(T), and the other (considered by Larkin and Ovchinnikov) of nonthermal nature at B << B(T). The results obtained have allowed us to interpret some peculiarities in the resistive transition, observed experimentally for wide superconducting films. Based on resistive measurements, a new way of finding the quasiparticle energy relaxation time is proposed. In the case of perfect acoustic matching of the film and the substrate, the inelastic scattering times of quasiparticles on both the quasiparticles and the phonons can be obtained separately.