Restoration f Superconductivity in High Parallel Magnetic Fields in Layered Superconductors

Abstract
We derive an equation determining the upper critical field Hc2(T) parallel to conducting planes of a layered superconductor from the BCS theory. It extends the descriptions of Hc2(T) within the Ginzburg-Landau-Abrikosov-Gor'kov theory and the Lawrence-Doniach model to the case of strong magnetic fields. From this equation, it follows that orbital effects of an electron motion along an open Fermi surface in a magnetic field start to restore superconductivity at megnetic fields higher than the quasiclassical upper critical and result in the appearance of a reentrant phase with Tc(H)=Tc(0). A stability of the reentrant phse against fluctuations is discussed.

Full Text [ PDF ]