Apparent negative mobility of vortex matter due to inhomogeneous pinning

X. B. Xu, H. Fangohr, S. Y. Ding, M. Gu, T. B. Tang, Z. H. Han, D. Q. Shi, and S. X. Dou
Phys. Rev. B 75, 224507 – Published 13 June 2007

Abstract

We investigate the transport of vortices in superconductors with inhomogeneous pinning under a driving force. The inhomogeneity of pinning is simplified as strong-weak pinning regions. It is demonstrated that the interactions between the vortices captured by strong pinning potentials and the vortices in the weak pinning region cause absolute negative motion (ANM) of vortices: The vortices which are climbing toward the high barriers induced by the strong pinning with the help of driving force move toward the opposite direction of the force and back to their equilibrium positions in the weak pinning region as the force decreases or is withdrawn. Our simulations reveal that the hysteresis of ANM is determined by the competition between the speed of the negative motion which depends on the pinning inhomogeneity in superconductors and the speed of the driving force. Under the conditions of either larger force scanning rate or higher pinning inhomogeneity, a marked ANM and a larger hysteretic speed-force loop could be observed. This indicates that the time window to observe the ANM should be chosen properly. Moreover, the VI characteristics of Ag-sheathed Bi-2223 tapes are measured, and experimental observations are qualitatively in agreement with the simulation.

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  • Received 17 January 2007

DOI:https://doi.org/10.1103/PhysRevB.75.224507

©2007 American Physical Society

Authors & Affiliations

X. B. Xu1,*, H. Fangohr2, S. Y. Ding1, M. Gu1, T. B. Tang3, Z. H. Han4, D. Q. Shi5, and S. X. Dou5

  • 1National Laboratory of Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093, People’s Republic of China
  • 2School of Engineering Sciences, University of Southampton, Southampton SO17 1BJ, United Kingdom
  • 3Department of Physics, Hong Kong Baptist University, Kowloon, Hong Kong SAR, People’s Republic of China
  • 4Applied Superconductivity Research Center, Tsinghua University, Beijing 100084, People’s Republic of China
  • 5Institute for Superconducting and Electronic Materials, University of Wollongong, New South Wales 2522, Australia

  • *Corresponding author; xxb@nju.edu.cn

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Issue

Vol. 75, Iss. 22 — 1 June 2007

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