The Superconducting Pinscape

Magnetic exclusion
Magnetic force lines go around the superconductor, not through it. Many superconductors completely exclude magnetic field, as shown on the left. The superconductors studied here allow magnetic lines to penetrate, but only in the form of bundles called vortices, as shown on the right.
Random Walk
Without the random walk, the vortices would drift in one direction only; with the random walk, instead of moving smoothly in one direction, they jump around a little. See pinning/pinning sites
Pinning/Pinning Sites
A pinning site is a defective place in the superconductor where vortices tend to stick. They tend to stick there because it requires less energy for the vortices to stay there. Weak pinning means that the defective place produces only a weak tendency to stick the vortices.
Brownian Motion
Brownian motion is the random walk taken by a particle which is constantly being buffeted by random collisions with neighboring particles. Einstein and Langevin first realized that the visible Brownian motion of dust particles must be driven by thermal collisions with invisible fluid molecules. This provided some of the first direct evidence for the existence of atoms. The magnetic vortices' random walk is not driven by thermal collisions but rather by their motion over the disordered energy landscape of the superconductor.
Energy Wells
An energy well is a region where the vortex has a low energy relative to surrounding regions. Extra energy is needed to remove a vortex from such a region. Pinning sites are energy wells.
Triangular Vortex Lattices
In a triangular vortex lattice, the vortices are arranged such that the vortices form equilateral triangles with each of their six closest neighbors, as can be seen by the black triangle in the image.
Boltzmann-like forms
The Boltzmann-like form of the distribution of the pinning energies means that the probability of a vortex having energy E falls exponentially as E increases.
The Movie's Protrusions
The protrusions aren't really sticking out. They represent the vortices, and here they are covered with yellow dots so they show up more clearly. That they look like they are sticking out is a result of the imaging process.


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