Static and dynamic behaviours of multivortex states in a superconducting sample with mesoscopic pinning sites

• Published in: The European physical journal. B, Condensed matter physics Vol. 83; no. 1; pp. 93 - 105
• Main Author: Yetis, H.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.09.2011; EDP Sciences; Springer
• Subjects: Complex Systems; Condensed Matter Physics; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Fluid- and Aerodynamics; Magnetic fields; Physics; Physics and Astronomy; Properties of type I and type II superconductors; Regular Article; Solid State Physics; Superconductivity; Superconductors; Toy industry; Vortex lattices ,flux pinning, flux creep; Vortex; Vortex State; Interstitial Region; Vortex Lattice; Vorticity; Superconducting thin films; Fluctuations; Flux pinning; Reentrant phases; Magnetic field effects; Vortex motion; Numerical method; Non linear effect; IV characteristic
• ISSN: 1434-6028; 1434-6036
• DOI: 10.1140/epjb/e2011-20290-y

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.