Abrikosov vortex

Vortices in a 200-nm-thick YBCO film imaged by scanning SQUID microscopy[1]

In superconductivity, an Abrikosov vortex is a vortex of supercurrent in a type-II superconductor theoretically predicted by Alexei Abrikosov in 1957.[2] The supercurrent circulates around the normal (i.e. non-superconducting) core of the vortex. The core has a size — the superconducting coherence length (parameter of a Ginzburg-Landau theory). The supercurrents decay on the distance about (London penetration depth) from the core. Note that in type-II superconductors . The circulating supercurrents induce magnetic fields with the total flux equal to a single flux quantum . Therefore, an Abrikosov vortex is often called a fluxon.

The magnetic field distribution of a single vortex far from its core can be described by

where is a zeroth-order Bessel function. Note that, according to the above formula, at the magnetic field , i.e. logarithmically diverges. In reality, for the field is simply given by

where κ = λ/ξ is known as the Ginzburg-Landau parameter, which must be in type-II superconductors.

Abrikosov vortices can be trapped in a type-II superconductor by chance, on defects, etc. Even if initially type-II superconductor contains no vortices, and one applies a magnetic field larger than the lower critical field (but smaller than the upper critical field ), the field penetrates into superconductor in terms of Abrikosov vortices. Each vortex carries one thread of magnetic field with the flux . Abrikosov vortices form a lattice, usually triangular, with the average vortex density (flux density) approximately equal to the externally applied magnetic field. As with other lattices, defects may form as dislocations.

See also

References

  1. Wells, Frederick S.; Pan, Alexey V.; Wang, X. Renshaw; Fedoseev, Sergey A.; Hilgenkamp, Hans (2015). "Analysis of low-field isotropic vortex glass containing vortex groups in YBa2Cu3O7x thin films visualized by scanning SQUID microscopy". Scientific Reports. 5: 8677. PMC 4345321Freely accessible. PMID 25728772. doi:10.1038/srep08677.
  2. Abrikosov, A. A. (1957). The magnetic properties of superconducting alloys. Journal of Physics and Chemistry of Solids, 2(3), 199-208.
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