Pairing and superconducting properties of 2 D Fermi-system with attraction

Proceeding from microscopic model Hamiltonian for the system of Fermi-particles with attraction the effective Lagrangian admitting the analysis of its superconducting properties at arbitrary fermion concentration is obtained. Exact solution of equations for the gap and chemical potential makes it possible to trace from local pair situation to Cooper pairing and superconductivity of BSC type. The crucial parameter discriminating the regions of normal and exotic superconducting behaviours is shown to be that of the energy of two-fermion bound state. The formulas obtained show that in the region of comparatively small concentrations the parameters of 2 D-metal correspond to 2 nd type superconductors