The ac effect of vortex pinning in the arrays of defect sites on Nb films

T. C. Wu, Lance Horng, J. C. Wu, C. W. Hsiao, Jan Koláček, T. J. Yang

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Niobium thin films with spacing-graded array of submicrometer-scaled holes had been fabricated using electron beam lithography through a lift-off technique. The magnetoresistance measurements and current-voltage characteristics were carried out with the external magnetic field applied perpendicular to the film plane, in which commensurable effects were observed in both experiments. The magnetoresistance with positive/negative directions of dc current revealed identical curves except the dips at matching fields separated. Two distinct current-voltage curves, which resulted from the positive and negative applied current directions, respectively, were discerned when the external magnetic field was fixed at the matching field, which is believed to be due to asymmetry pinning potential in the spacing-graded array of holes. In addition, ac current-voltage curve measured at matching field showed a ratchet bump along with another extra peak associated with incommensurable effect.

Original languageEnglish
Article number08M515
JournalJournal of Applied Physics
Issue number8
Publication statusPublished - 2006

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Fingerprint Dive into the research topics of 'The ac effect of vortex pinning in the arrays of defect sites on Nb films'. Together they form a unique fingerprint.

Cite this