SURFACE INDUCED ANOMALOUS SUPERCONDUCTIVITY
The Ginzburg–Landau (GL) theory is recast using a Hamiltonian involving the complete kinetic energy density which requires that the surface energy must contain a term ∇|ψ|2 to support superconducting (SC) states. The GL equations contain two temperature t dependent parameters α(t) and β(t), which are respectively the coefficients of the SC pair density ∝|ψ|2, and the pair interaction term ∝|ψ|4 in the free energy density. The sign of these parameters, which defines distinct solution classes, and the ratio are governed by the characteristics of the surface energy density. In addition to the conventional bulk superconducting states with (α 0), anomalous superconducting states exist for all other sign combinations, including cases with β < 0 which may exist only when surface pair interactions are significant. All possible solutions of our generalized nonlinear, one-dimensional GL equations are found analytically and applied to a thin superconducting slab which manifests the possibility of states exhibiting enhanced, diminished, and pre-wetting superconductivity. Critical currents are determined as functions of s(t) and surface parameters. The results are applied to critical current experiments on SNS systems.