Superconductivity in Dense MgB2 Wires

Phys. Rev. Lett. 86, 2423 – Published 12 March 2001
P. C. Canfield, D. K. Finnemore, S. L. Bud'ko, J. E. Ostenson, G. Lapertot, C. E. Cunningham, and C. Petrovic

Abstract

MgB2 becomes superconducting just below 40 K. Whereas porous polycrystalline samples of MgB2 can be synthesized from boron powders, in this Letter we demonstrate that dense wires of MgB2 can be prepared by exposing boron filaments to Mg vapor. The resulting wires have a diameter of 160 μm, are better than 80% dense, and manifest the full χ=-1/4π shielding in the superconducting state. Temperature-dependent resistivity measurements indicate that MgB2 is a highly conducting metal in the normal state with ρ(40 K)=0.38 μΩ cm. By using this value, an electronic mean-free path, l600 can be estimated, indicating that MgB2 wires are well within the clean limit. Tc, Hc2(T), and Jc data indicate that MgB2 manifests comparable or better superconducting properties in dense wire form than it manifests as a sintered pellet.

DOI: http://dx.doi.org/10.1103/PhysRevLett.86.2423

  • Received 12 February 2001
  • Published in the issue dated 12 March 2001

© 2001 The American Physical Society

Authors & Affiliations

P. C. Canfield, D. K. Finnemore, S. L. Bud'ko, J. E. Ostenson, G. Lapertot*, C. E. Cunningham, and C. Petrovic

  • Ames Laboratory, U.S. Department of Energy and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011

  • *On leave from Commissariat a l'Energie Atomique, DRFMC-SPSMS, 38054 Grenoble, France.
  • On leave from Department of Physics, Grinnell College, Grinnell, Iowa 50112.

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