Pinning in High-Tc Superconductors
Magnetic flux can penetrate a type-II superconductor in the form of flux-lines or Abrikosov vortices, each of which carry a quantum of flux and arrange in a more or less regular triangular lattice. Under the action of an electric current, these flux lines move and dissipate energy unless they are pi...
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| Main Author: | |
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| Format: | Article |
| Language: | English |
| Published: |
Wiley
1993-01-01
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| Series: | Active and Passive Electronic Components |
| Online Access: | http://dx.doi.org/10.1155/1993/45791 |
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| Summary: | Magnetic flux can penetrate a type-II superconductor in the form of flux-lines or Abrikosov vortices,
each of which carry a quantum of flux and arrange in a more or less regular triangular lattice. Under
the action of an electric current, these flux lines move and dissipate energy unless they are pinned by
material inhomogeneities. In conventional superconductors, depinning occurs when a critical current
density Jc is exceeded. In high-Tc superconductors (HTSC), thermally activated depinning causes a finite
resistivity t9 even at current densities J ≪ Jc. At sufficiently large temperature T, linear (ohmic) resistivity
is observed down to J → 0. This indicates that the flux lines are in a "liquid state" with no shear stiffness
and with small depinning energy. At lower T, ρ(J) is highly nonlinear, since the pinning energy increases
with decreasing J. In highly anisotropic Bi- and Tl-based HTSC, thermal depinning occurs at rather
low T, since short vortex segments ("pancake vortices" in the CuO layers) can depin individually with
very small activation energy. |
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| ISSN: | 0882-7516 1563-5031 |