Model of the mixed state of type-II superconductors in high magnetic fields

Abstract

In superconductors with large values of the Ginzburg-Landau parameter, exposed to magnetic fields close to the upper critical field, the magnetic field is practically homogeneous across the sample and the density of supercurrents is negligibly small. In this case, there is no obvious reason for the formation of Abrikosov vortices, characteristic for the commonly known mixed state. We consider an alternative model for describing the mixed state. We argue that with decreasing magnetic field the traditional vortex structure is adopted via a first order phase transition, revealed by discontinuities in the magnetization as well as the resistivity.