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We report numerical simulations of a trapped elastic vortex driven by a strong ac magnetic field $H(t)=Hsinomega t$ parallel to the surface of a superconducting film. The surface resistance and the power dissipated by an oscillating vortex perpendicular to the film surface were calculated as functions of $H$ and $omega$ for different spatial distributions, densities, and strengths of pinning centers, including bulk pinning, surface pinning, and cluster pinning. Our simulations were performed for both the Bardeen-Stephen viscous vortex drag and the Larkin-Ovchinnikov (LO) drag coefficient $eta(v)$ decreasing with the vortex velocity $v$. The local residual surface resistance $R_i(H)$ calculated for different statistical realizations of the pinning potential exhibits strong mesoscopic fluctuations caused by local depinning jumps of a vortex segment as $H$ increases, but the global surface resistance $bar{R}_i(H)$ obtained by averaging $R_i(H)$ over different pin configurations increases smoothly with the field amplitude at small $H$ and levels off at higher fields. For strong pinning, the LO decrease of $eta(v)$ with $v$ can result in a nonmonotonic field dependence of $R_i(H)$ which decreases with $H$ at higher fields, but cause a runaway instability of the vortex in a thick film for weak pinning. It is shown that overheating of a single moving vortex can produce the LO-like velocity dependence of $eta(v)$, but can mask the decrease of the surface resistance with $H$ at a higher density of trapped vortices.
We report numerical simulations of large-amplitude oscillations of a trapped vortex line under a strong ac magnetic field $H(t)=Hsinomega t$ parallel to the surface. The power dissipated by an oscillating vortex segment driven by the surface ac Meiss
In this paper, we describe the vortex dynamics under high-amplitude microwave drive and its effect on the surface resistance of superconductors. The vortex surface resistance is calculated with a Montecarlo approach, where the vortex motion equation
By the application of a small oscillating magnetic field parallel to the main magnetic field and perpendicular to the transport current, we were able to generate a voltage dip in the I-V curves of Nb$_3$Sn similar to the peak-effect pattern observed
We study effects of pinning on the dynamics of a vortex lattice in a type II superconductor in the strong-pinning situation and determine the force--velocity (or current--voltage) characteristic combining analytical and numerical methods. Our analysi
Demanding microwave applications in a magnetic field require the material optimization not only in zero-field but, more important, in the in-field flux motion dominated regime. However, the effect of artificial pinning centers (APC) remains unclear a