Abstract
The discovery of superconductivity at 39âK in magnesium diboride1, MgB2, raises many issues, a critical one being whether this material resembles a high-temperature copper oxide superconductor or a low-temperature metallic superconductor in terms of its behaviour in strong magnetic fields. Although the copper oxides exhibit very high transition temperatures, their in-field performance2 is compromized by their large anisotropy, the result of which is to restrict high bulk current densities to a region much less than the full magnetic-fieldâtemperature (HâT) space over which superconductivity is found. Moreover, the weak coupling across grain boundaries makes transport current densities in untextured polycrystalline samples low and strongly sensitive to magnetic field3,4. Here we report that, despite the multiphase, untextured, microscale, subdivided nature of our MgB2 samples, supercurrents flow throughout the material without exhibiting strong sensitivity to weak magnetic fields3. Our combined magnetization, magneto-optical, microscopy and X-ray investigations show that the supercurrent density is mostly determined by flux pinning, rather than by the grain boundary connectivity. Our results therefore suggest that this new superconductor class is not compromized by weak-link problems, a conclusion of significance for practical applications if higher temperature analogues of this compound can be discovered.
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References
Nagamatsu, J., Nakagawa, N., Muranaka, T., Zenitani, Y. & Akimitsu, J. Superconductivity at 39âK in magnesium diboride. Nature 410, 63â64 (2001).
Yeshurun, Y., Malozemoff, A. P. & Shaulov, A. Magnetic relaxation in high-temperature superconductors. Rev. Mod. Phys. 68, 911â949 (1996).
Dimos, D., Chaudhari, P. & Mannhart, J. Super-conducting transport properties of grain boundaries in YBa2Cu3O7 bicrystals. Phys. Rev. B 41, 4038â4049 (1990).
Heinig, N. F., Redwing, R. D., Nordman, J. E. & Larbalestier, D. C. Strong to weak coupling transition in YBa2Cu3O7 bicrystals. Phys. Rev. B 60, 1409â1417 (1999).
Bud'ko, S. L. et al. Boron isotope effect in superconducting MgB2. Phys. Rev. Lett. 86, 1877â1880 (2001).
Werthamer, N. R., Helfand, E. & Hohenberg, P. C. Temperature and purity dependence of the superconducting critical field, Hc2. Phys. Rev. 147, 288â294 (1966).
Finnemore, D. K., Ostenson, J. E., Bud'ko, S. L., Lapertot, G. & Canfield, P. C. Thermodynamic and transport properties of superconducting Mg10B2. Phys. Rev. Lett. (in the press).
Dew-Hughes, D. The role of grain boundaries in determining Jc in high-field, high-current superconductors. Phil. Mag. 55, 459â479 (1987).
Suenaga, M., Ghosh, A. K., Xu, Y. & Welch, D. O. Irreversibility temperatures of Nb3Sn and Nb-Ti. Phys. Rev. Lett. 66, 1777â1780 (1991).
Campbell, A. M. & Evetts, J. E. Flux vortices and transport currents in type II superconductors. Adv. Phys. 21, 199â428 (1972).
Acknowledgements
Work at the University of Wisconsin was supported by the US Air Force Office of Scientific Research, the US Department of Energy, and the US National Science Foundation through the MRSEC programme; work at Princeton University was supported by the US Department of Energy and the US National Science Foundation.
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Larbalestier, D., Cooley, L., Rikel, M. et al. Strongly linked current flow in polycrystalline forms of the superconductor MgB2. Nature 410, 186â189 (2001). https://doi.org/10.1038/35065559
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DOI: https://doi.org/10.1038/35065559
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