论文标题
动态成对的电流，临界超流速速度和非平衡超导体的非线性电磁响应
Dynamic pair-breaking current, critical superfluid velocity and nonlinear electromagnetic response of nonequilibrium superconductors
论文作者
论文摘要
我们报告了动态成对的电流密度$ j_d $的数值计算和一个关键的超级流体速度$ v_d $在非等级超导体中，带有均匀的，较大的AC电流密度$ j（t）= j_a \sinΩt$，其$ phar $ phap $ $ω__0/依赖性$ j_d（ω，t）$和$ v_d（ω，t）$附近的临界温度$ t_c $是根据全职依赖性的非平衡方程来计算的，用于肮脏的S波超导体的肮脏S-波超导体和时间依赖的Ginzburg-landau（TDGL）方程的时间，以供量的超级参与者，可容纳量度的超级参数，可占用量度的超级参与。 $τ_{gl} $和准粒子的非弹性电子释放时间$τ_e$。我们表明，两种方法都给出了$ j_d（ω）$和$ v_d（ω）$的相似频率依赖性，它们逐渐从其静态成对的GL值$ j_c $和$ V_C $和$ωτ_e\ ll 1 $ to $ \ ll 1 $ to $ \ \ sqrt {2} j_c $和$ \ c $ and $ \ sqrt $ qurt $ qurt $ quc $ quc $ $ quc $ $ quc $这里$ j_d $，$ v_d $和一个动态的过热领域，在该领域中，Meissner状态变得不稳定，以两个固定的AC电流和固定的AC超富速度的固定速度进行计算。我们还计算了非平衡超导状态的非线性电磁反应，尤其是动态动力学电感和耗散的准粒子电导率，同时考虑了超导凝管的振荡动力学以及由强AC电流驱动的Quasipartics的振荡动力学。结果表明，交流电流密度会产生电场的多个谐波，随着$τ_e$的增加，高阶谐波的幅度减小。
We report numerical calculations of a dynamic pairbreaking current density $J_d$ and a critical superfluid velocity $v_d$ in a nonequilibrium superconductor carrying a uniform, large-amplitude ac current density $J(t)=J_a\sinΩt$ with $Ω$ well below the gap frequency $Ω\ll Δ_0/\hbar$. The dependencies $J_d(Ω,T)$ and $v_d(Ω,T)$ near the critical temperature $T_c$ were calculated from either the full time-dependent nonequilibrium equations for a dirty s-wave superconductor and the time-dependent Ginzburg-Landau (TDGL) equations for a gapped superconductor, taking into account the GL relaxation time of the order parameter $τ_{GL}$ and the inelastic electron-phonon relaxation time of quasiparticles $τ_E$. We show that both approaches give similar frequency dependencies of $J_d(Ω)$ and $v_d(Ω)$ which gradually increase from their static pairbreaking GL values $J_c$ and $v_c$ at $Ωτ_E\ll 1$ to $\sqrt{2}J_c$ and $\sqrt{2}v_c$ at $Ωτ_E\gg 1$. Here $J_d$, $v_d$ 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 $H=H_a\sinΩt$ 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 $τ_E$ increases.
