A third example is the magnetically-induced Wigner crystal in a two-dimensional electron gas (2DEG). In large magnetic fields, the electronic spectrum changes from a band-like form to that of discrete, highly degenerate Landau levels. These states are tightly localized spatially, and correspond semi-classically to tight cyclotron orbits of the electrons. The degeneracy can be simply interpreted as the number of approximately non-overlapping cyclotron orbits which fit into the plane.
Wigner crystal states are of considerable interest experimentally because they are the principle competitor with the quantum Hall states in 2DEGs. Their statistical mechanics is very similar to that of the two-dimensional vortex lattice.