Topological gauge theory of vortices in type-III superconductors

Abstract

Traditional superconductors fall into two categories, type-I, expelling magnetic fields, and type-II, into which magnetic fields exceeding a lower critical field $H_{\rm c1}$ penetrate in form of Abrikosov vortices. Abrikosov vortices are characterized by two spatial scales, the size of the normal core, $\xi$, where the superconducting order parameter is suppressed and the London penetration depth $\lambda$, describing the scale at which circulating superconducting currents forming vortices start to noticeably drop. Here we demonstrate that a novel type-III superconductivity, realized in granular media in any dimension hosts a novel vortex physics. Type-III vortices have no cores, are logarithmically confined and carry only a gauge scale $\lambda$. Accordingly, in type-III superconductors $H_{\rm c1}=0$ at zero temperature and the Ginzburg-Landau theory must be replaced by a topological gauge theory. Type-III superconductivity is destroyed not by Cooper pair breaking but by vortex proliferation generalizing the Berezinskii-Kosterlitz-Thouless mechanism to any dimension.