Exact analytic Gorkov-Ginzburg-Landau theory of type-II superconductivity in the magnetoquantum oscillations limit

Abstract

A new Green's function representation is employed in a microscopic derivation of a Ginzburg-Landau theory of strongly type-II superconductivity at high magnetic fields. An exact analytical, physically transparent expression for the quartic term in the corresponding order parameter expansion is presented. The resulting expression reveals nonlocal contributions to the superconducting (SC) free energy, associated with highly coherent cyclotron motions of the paired electrons near the Fermi surface, which lead to singular couplings to the vortex lattice. A major part of these contributions arises from incoherent scattering by the spatially averaged pair potential, which is purely harmonic in the de Haas--van Alphen frequency. However, coherent scatterings by the ordered vortex lattice generate a large erratically oscillating (i.e., paramagnetic-diamagnetic) contribution to the SC free energy as a function of the magnetic field. Vortex lattice disorder, which tends to suppress this oscillatory component, is found to preserve the harmonic part of the SC free energy.