Collective flux pinning
Vicent, José Luis Departmento de Física de Materiales, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, Madrid, Spain.
- Vortices and vortex lattices
- Artificial nanostructures as pinning centers
- Motion on asymmetric pinning potentials
- Links to Primary Literature
- Additional Readings
Type II superconductors exhibit two superconducting phases in applied magnetic fields. The first is a state of perfect diamagnetism (Meissner phase), the same state as is found in type I superconductors, with complete exclusion of the magnetic flux. However, if the value of the applied magnetic field is increased, a transition to a second state develops, in which the magnetic field threads inside the superconductor and is associated with a regular array of supercurrent vortices, a vortex lattice, with each vortex surrounding one quantum of magnetic flux (Φ0 = 2.07 × 10−7 gauss cm2 = 2.07 × 10−15 weber). This state is called the mixed, vortex, or Abrikosov state. In the core of these vortices the superconducting state vanishes and the current carriers are electrons; outside the vortices the sample remains superconducting and the carriers are Cooper pairs. Therefore, if the vortices are pushed and they move, electrical resistance and dissipation will develop in the sample, and superconductivity will be lost. This will, indeed, occur in the presence of a very small current if the vortices are not anchored by some mechanism. Thus, one of the most relevant topics in applied superconductivity is to look for pinning mechanisms that will anchor or pin the vortices and preserve the superconducting state, although the sample is in the mixed state. Ordinarily, pinning is provided through randomly distributed defects in the crystal lattice of the superconductor. New fabrication techniques in the realm of nanotechnology allow the fabrication of nanostructured superconductors with periodic arrays of pinning centers. In the presence of such arrays, the phenomenon of collective flux pinning can occur: The whole vortex lattice can be pinned collectively. This phenomenon offers a promising approach to tailor pinning mechanisms at will.
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Its dedicated editorial team is led by Sagan Award winner John Rennie. Contributors include more than 9000 highly qualified scientists and 42 Nobel Prize winners.
MORE THAN 8500 articles and Research Reviews covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 17,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information