Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1820993 | Physica C: Superconductivity and its Applications | 2006 | 4 Pages |
Abstract
We have investigated the vortex dynamics in the niobium films having a spacing-graded array of pinning sites. The samples were fabricated by using electron beam lithography through a lift-off technique. The pinning sites of 200Â nm in diameter were arranged with a constant hole-defect separation in x-axis direction and graded separation in y-axis direction from 392Â nm to 408Â nm. The magnetoresistance measurements and current-voltage characteristics were explored with the external magnetic field applied perpendicular to the film plane. Dc current-voltage measured at matching field revealed two distinct curves resulted from the positive and negative applied current directions, respectively. This is believed to be due to an asymmetry pinning potential formed in the spacing-graded array of holes, giving rise to asymmetry Lorentz forces. Dc voltage drop measured with respect to the ac current applied along the x-axis of the sample showed two separated maxima, which can be explained using the dynamics of pinned vortex lattice and interstitial vortices in the asymmetry pinning landscape.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Condensed Matter Physics
Authors
T.C. Wu, Lance Horng, J.C. Wu, C.W. Hsiao, Jan Kolacek, T.J. Yang,