Physical Review B
104507 (15 pp.)
We report numerical calculations of a dynamic pair-breaking current density Jd and a critical superfluid velocity vd in a nonequilibrium superconductor carrying a uniform, large-amplitude AC current density J(t)=JasinΩt with Ω well below the gap frequency Ω ≪ Δ0/h. The dependencies Jd(Ω,T) and vd(Ω,T) near the critical temperature Tcwere calculated from either the full time-dependent nonequilibrium equations for a dirty s-wave superconductor or the time-dependent Ginzburg-Landau (TDGL) equations for a gapped superconductor, taking into account the GL relaxation time of the order parameter GL and the inelastic electron-phonon relaxation time of quasiparticles 𝒯E. We show that both approaches give similar frequency dependencies of Jd(Ω) and vd(Ω) which gradually increase from their static pair-breaking GL values Jc and vcat E1 to 2Jc and vc at Ω𝒯E≪ 1 to √2Jc and √2vc at Ω𝒯E ≫ 1. Here Jd, vd and a dynamic superheating field at which the Meissner state becomes unstable were calculated in two different regimes of a fixed AC current and a fixed AC superfluid velocity induced by the applied AC magnetic field H=HasinΩt in a thin superconducting filament or a type-II superconductor with a large GL parameter. We also calculated a nonlinear electromagnetic response of a nonequilibrium superconducting state, particularly a dynamic kinetic inductance and a dissipative quasiparticle conductivity, taking into account the oscillatory dynamics of superconducting condensate and the kinetics of quasiparticles driven by a strong AC current. It is shown that an AC current density produces multiple harmonics of the electric field, the amplitudes of the higher-order harmonics diminishing as 𝒯E increases.
Original Publication Citation
Sheikhzada, A., & Gurevich, A. (2020). Dynamic pair-breaking current, critical superfluid velocity, and nonlinear electromagnetic response of nonequilibrium superconductors. Physical Review B, 102(10), (15 pp.), Article 104507 https://doi.org/10.1103/PhysRevB.102.104507
Sheikhzada, Ahmad and Gurevich, Alex, "Dynamic Pair-Breaking Current, Critical Superfluid Velocity, and Nonlinear Electromagnetic Response of Nonequilibrium Superconductors" (2020). Physics Faculty Publications. 449.