Static and dynamic behaviours of multivortex states in a superconducting sample with mesoscopic pinning sites |
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Authors: | H Yetis |
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Institution: | (1) Department of Physics, Abant Izzet Baysal University, 14280 Bolu, Turkey |
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Abstract: | This preliminary work has focused on the static
transitions between the multivortex states interacting with square
arrays of the mesoscopic pinning sites in superconducting samples.
Our results were obtained from an extensive series of numerical
simulations as functions of the magnetic field, pinning radius,
and sample size. We have presented a wide range of multivortex
configurations from commensurate dimer states to more concentric
vortex shells at the matching fields. The stability of these
states was also studied by means of the current-voltage V(I)
curves which illustrate dynamic phase transitions as a function of
applied driving force. These transitions manifested themselves as
either a sudden jump in velocity or a nonlinear increase with
velocity fluctuations in V(I) curves. We have investigated
whether that the phase transitions between the pinned regime and
the elastic flow regime are indicative of the stability of the
initial vortex states. The variety of intermediate flow phases is
attributed to large pinning size (reentrant behavior), strong
commensurability and caging effects. In particular, three-shell
vortex structures were obtained in the presence of larger pinning
sites at adequate matching magnetic fields. |
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Keywords: | |
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