Vortex-antivortex dynamics in mesoscopic symmetric and asymmetric superconducting loops with an applied ac current
1 Department of Physics, Shanghai University - Shanghai 200444, China
2 Departement Fysica, Universiteit Antwerpen - Groenenborgerlaan 171, B-2020 Antwerpen, Belgium
Received: 16 September 2014
Accepted: 10 November 2014
In the framework of the time-dependent Ginzburg-Landau formalism, we study the dynamics of vortex-antivortex (V-Av) pairs in mesoscopic symmetric and asymmetric superconducting loops under an applied ac current. In contrast to the case of a constant biasing dc current, the process of the V-Av collision and annihilation is strongly affected by the time-periodic ac signal. As the direction of the applied ac current is reversed, the existed V-Av pair moves backward and then collides with a new created Av-V pair in a symmetric loop. In the presence of an appropriate external magnetic field, a novel sinusoidal-like oscillatory mode of the magnetization curve is observed, and the periodic dynamical process of the V-Av annihilation occurs in both branches of the sample. Moreover, for the asymmetric sample with an off-centered hole the creation point of the V-Av pair shifts away from the center of the sample, and the creation and annihilation dynamics of V-Av pairs turns out to be very different from the symmetric case.
PACS: 74.20.De – Phenomenological theories (two-fluid, Ginzburg-Landau, etc.) / 74.78.Na – Mesoscopic and nanoscale systems
© EPLA, 2014