Crystals of magnetic flux

It is shown that the magnetic field in certain strongly magnetic materials, i.e. type-II superconductors and highly anisotropic ferromagnetics, can acquire a modulation which is periodic in two dimensions. The material can be thought of as being filled with a two-dimensional crystal of magnetic flux. These crystals of magnetic flux display many of the familiar properties of crystalline material: suitable waves can be diffracted from them, they can contain the familiar defect of crystal lattices, and the bulk properties of the material can be affected by the microscopic periodicity. 77 references. (author)