Ground State and Transport Property in Superconductors with Artificial Pinning Arrays

The dynamics of a two-dimensional vortex system in superconductors with periodic artificial columnar pinning is studied. The ground state at field B = 3Bf can be either anisotropic or isotropic, dependent on pinning strength and size, here Bf is the matching field where the number of vortices equals that of pins. The transport curves are dependent on the ground vortex structures and anisotropic ground structure may result in anisotropic velocity-force curve. Results indicate that the ground structure can be detected from the transport property. We also discover that a jump in velocity-force curve accompanies a structure transition.