Nonlinear Dynamics and Dissipation of a Curvilinear Vortex Driven by a Strong Surface Current

We report extensive numerical simulations of large-amplitude oscillations of a trapped vortex line subject to a strong ac magnetic field H(t) = H₀sin(ωt) parallel to the surface. The power dissipated by an oscillating vortex segment driven by the Meissner current was calculated by taking into account the nonlinear vortex line tension, vortex mass and a nonlinear Larkin-Ovchinnikov (LO) viscous drag force. It is shown that oscillations of trapped vortices perpendicular to the surface can radically change the field dependence of a residual surface resistance R_i(H₀) due to the LO decrease of the viscous drag coefficient with the vortex velocity. As the frequency increases,the conventional increase of R_i(H₀) with H₀ at low ω evolves into a non-monotonic dependence of R_i(H₀) at larger ω, so that R_i(H₀) decreases with H₀ at higher fields. As the electron mean free path on nonmagnetic impurities gets shorter, the field onset of the anomalous decrease of R_i(H₀) shifts to smaller field, and the drop of R_i(H₀) with H₀ becomes more pronounced.