Dynamic nonequilibrium distributions and nonlinear electromagnetic absorption in superconducting films at low temperatures
Abstract
The dynamic nonequilibrium distributions of electronic excitations in superconducting films, arising owing to the oscillations of the density of states and of the boundary of the energy spectrum of the superconductor in an alternating electromagnetic field, are studied. At low temperatures T≪ Δ, comparable to the amplitude of the oscillations of the boundary of the spectrum, the distrubution and density of quasiparticles differ substantially from the nonequilibrium values. The amplitude and temperature dependences of the nonlinear relaxational electromagnetic absorption, determined by nonadiabatic oscillations of the density of the superfluid component of the current and transfer of kinetic energy from the condensate to the excitations, are found.