ON THE REMARKABLE STRUCTURE OF THE SUPERCONDUCTING INTERMEDIATE STATE

If a large square plate of a type I superconductor is placed in a perpendicular magnetic field, the field will penetrate it in a pattern of domains. The intermediate-state problem is to predict this pattern. In the critical Ginzburg-Landau theory, the horizontal and momentum directions of the plate are essentially Fourier conjugate coordinates, like position and momentum in quantum mechanics. Thus, the intermediate state allows us a rare direct glimpse of quantum phase space. It is also demonstrated that, although Landau's (1937) textbook model is inconsistent with the Ginzburg-Landau equations, its qualitative nature is correct. Elongated structures consistent with a complete spontaneous breakdown of discrete rotational invariance are predicted. Comments with regard to lattice Higgs simulations are also made. © 1990.