SUPERCONDUCTIVITY AND METAL-INSULATOR PHASE-TRANSITION IN A LAYERED 2-DIMENSIONAL FERMI GAS

Using the Fermi-liquid approach with vertex corrections, the effects o f exchange and correlation are considered in a layered two-dimensional electron gas. It is shown that the interaction in the particle-hole c hannel can induce the metal-insulator phase transition when the Fermi momentum is comparable with the inverse interlayer spacing, p(F) appro ximate to 1/c. The possibility of superconductivity in the region betw een the insulator and normal metal phases, taking into account the par ticle-hole excitations, is discussed. A smooth crossover from weak to strong coupling superconductivity with the decrease of the 2D carrier density is obtained. The results suggest a new way in the explanation of the phase diagram of layered high-T-c superconductors.