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Parallel magnetic field suppresses dissipation in superconducting nanostrips

  1. Wai-Kwong Kwoka
  1. aMaterials Science Division, Argonne National Laboratory, Argonne, IL 60439;
  2. bDepartment of Physics, University of Notre Dame, Notre Dame, IN 46556;
  3. cResearch Institute of Superconductor Electronics, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China;
  4. dDepartment of Physics, Northern Illinois University, DeKalb, IL 60115;
  5. eDepartment of Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, IL 60208;
  6. fDepartment of Biomedical Engineering, Pennsylvania State University, University Park, PA 16802;
  7. gQatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Doha, Qatar;
  8. hDepartement Fysica, Universiteit Antwerpen, B-2020 Antwerp, Belgium;
  9. iDepartment of Physics, University of Illinois, Chicago, IL 60607;
  10. jDepartment of Electrical Engineering, University of Illinois, Chicago, IL 60607;
  11. kDepartment of Mechanical Engineering, University of Illinois, Chicago, IL 60607
  1. Contributed by George W. Crabtree, October 13, 2017 (sent for review December 1, 2016; reviewed by Eva Y. Andrei, Allen M. Goldman, and M. Brian Maple)

Significance

Absolute zero resistance of superconducting materials is difficult to achieve in practice due to the motion of microscopic Abrikosov vortices, especially when external currents are applied. Even a partial resistance reduction via vortex immobilization by microscopic material imperfections is the holy grail of superconductivity research. It is commonly believed that the dissipation increases with applied magnetic field since the number of vortices increases as well. Through the example of molybdenum–germanium superconducting nanostrips, we show that resistive losses due to vortex motion can actually be decreased by applying an increasing applied magnetic field parallel to the current. This surprising recovery of superconductivity is achieved through “vortex crowding”: The increased number of vortices impedes their mutual motion, resulting in straight, untwisted vortices.

Abstract

The motion of Abrikosov vortices in type-II superconductors results in a finite resistance in the presence of an applied electric current. Elimination or reduction of the resistance via immobilization of vortices is the “holy grail” of superconductivity research. Common wisdom dictates that an increase in the magnetic field escalates the loss of energy since the number of vortices increases. Here we show that this is no longer true if the magnetic field and the current are applied parallel to each other. Our experimental studies on the resistive behavior of a superconducting Mo0.79Ge0.21 nanostrip reveal the emergence of a dissipative state with increasing magnetic field, followed by a pronounced resistance drop, signifying a reentrance to the superconducting state. Large-scale simulations of the 3D time-dependent Ginzburg–Landau model indicate that the intermediate resistive state is due to an unwinding of twisted vortices. When the magnetic field increases, this instability is suppressed due to a better accommodation of the vortex lattice to the pinning configuration. Our findings show that magnetic field and geometrical confinement can suppress the dissipation induced by vortex motion and thus radically improve the performance of superconducting materials.

Footnotes

  • ?1To whom correspondence should be addressed. Email: crabtree{at}uic.edu.
  • Author contributions: Y.-L.W., Z.-L.X., G.W.C., and W.-K.K. designed research; Y.-L.W., A.G., and L.R.T. performed research; Y.-L.W., A.G., G.J.K., G.R.B., and F.M.P. analyzed data; and Y.-L.W., A.G., I.S.A., Z.-L.X., G.W.C., and W.-K.K. wrote the paper.

  • Reviewers: E.Y.A., Rutgers University; A.M.G., University of Minnesota; and M.B.M., University of California, San Diego.

  • The authors declare no conflict of interest.

  • This article contains supporting information online at www.danielhellerman.com/lookup/suppl/doi:10.1073/pnas.1619550114/-/DCSupplemental.

Published under the PNAS license.

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