Letter abstract

Nature Physics 3, 239 - 242 (2007)
Published online: 11 February 2007 | doi:10.1038/nphys540

Subject Categories: Condensed-matter physics | Statistical physics, thermodynamics and nonlinear dynamics | Materials physics

Two-dimensional vortices in superconductors

Bo Chen1, W. P. Halperin1, Prasenjit Guptasarma2, D. G. Hinks3,
V. F. Mitrovic acute4, A. P. Reyes5 & P. L. Kuhns5


Superconductors have two key characteristics: they expel magnetic field and they conduct electrical current with zero resistance. However, both properties are compromised in high magnetic fields, which can penetrate the material and create a mixed state of quantized vortices. The vortices move in response to an electrical current, dissipating energy and destroying the zero-resistance state1. One of the central problems for applications of high-temperature superconductivity is the stabilization of vortices to ensure zero electrical resistance. We find that vortices in the anisotropic superconductor Bi2Sr2CaCu2O8+delta (Bi-2212) have a phase transition from a liquid state, which is inherently unstable, to a two-dimensional vortex solid. We show that at high field the transition temperature is independent of magnetic field, as was predicted theoretically for the melting of an ideal two-dimensional vortex lattice2, 3. Our results indicate that the stable solid phase can be reached at any field, as may be necessary for applications involving superconducting magnets4, 5, 6. The vortex solid is disordered, as suggested by previous studies at lower fields7, 8. But its evolution with increasing magnetic field exhibits unexpected threshold behaviour that needs further investigation.

  1. Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, USA
  2. Department of Physics, University of Wisconsin-Milwaukee, Wisconsin 53211, USA
  3. Materials Science and Technology Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
  4. Department of Physics, Brown University, Providence, Rhode Island 02912, USA
  5. National High Magnetic Field Laboratory Tallahassee, Florida 32310, USA

Correspondence to: W. P. Halperin1 e-mail: w-halperin@northwestern.edu


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