Controlled vortex motion in multiple interpenetrating pinning arrays
Abant Izzet Baysal University, Department of Physics, Turgut Gulez
Research Laboratory, 14280
Received in final form: 25 May 2013
Published online: 1 August 2013
We study the effect of multiple interpenetrating pinning arrays on the vortex motion in the presence of an ac driving force, fd(t), by using extensive molecular dynamics (MD) simulations. Firstly, the response to a square ac wave fd(t) has been explored for the vortices interacting with a periodic square pinning array which has different pinning strengths and sizes. The effect of the type of an ac drive and its amplitude on the oscillatory dynamics of vortices have been investigated in detail. For very low displacements of the vortices, we have found that the single-particle model can produce results analytically similar to the ones obtained by the MD simulations. It is shown that the collective motion of vortices can be controlled easily by varying the number of multiple interpenetrating square pinning lattices (NSPSL). A regular sequence of peaks has been observed for NSPSL = 3 in the time evolution of the average velocity of the vortices (i.e., V̅x - t curves). The number of peaks (Npeak) strongly depends on the magnitude of fd(t), and increases with increasing the magnitude of fd. The close relation between Npeak and fd is considered as an indication of controlling vortex motion in a multiple periodic pinning structure. Finally, the variation of the power spectrum of noise S(ν) with NSPSL has been investigated. For NSPSL = 3, it has been found that the plastic motion of the row of vortices evolves at low frequencies, i.e., 1/ν behavior, whereas, at high frequencies, S(ν) shows a typical behavior of Gaussian white noise.
Key words: Computational Methods
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2013