Theory of superconductors with κ close to 1/2

Abstract

As was first shown by Bogomolnyi, the critical Ginzburg-Landau (GL) parameter κ=1/2 at which a superconductor changes its behavior from type I to type II, is the special highly degenerate point where Abrikosov vortices do not interact and therefore all vortex states have the same energy. Developing a secular perturbation theory, we studied how this degeneracy is lifted when κ is slightly different from 1/2 or when the GL theory is extended to the higher terms in T−Tc. We constructed a simple secular functional that depends only on few experimentally measurable phenomenological parameters and therefore is quite efficient to study the vortex state of superconductor in this transitional region of κ. On this base, we calculated such vortex state properties as critical fields, energy of the normal-superconductor interface, energy of the vortex lattice, vortex interaction energy, etc., and compared them with previous results that were based on bulky solutions of GL equations.

Source-reported materials — not catalogue approval

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