QUANTUM SUPERCONDUCTOR-METAL TRANSITION IN A 2D PROXIMITY-COUPLED ARRAY

We construct a theory of quantum fluctuations in a regular array of sm all superconductive islands of size d connected via low-resistance tun nel contacts (G(t) = h/4e R-2(t) much greater than 1) to a dirty thin metal film with dimensionless conductance g much greater than 1. Elect rons in the film interact repulsively with the dimensionless strength lambda. The system is macroscopically superconductive when the distanc e b between neighbouring islands is short enough. The zero-temperature phase transition from the superconductive to the normal-conductive st ate is shown to occur with the increase of distance between supercondu ctive islands, at In b(c)/d similar to G(t)(2)/lambda g. The critical distance b(c) is much less than the 2d localization length L-loc simil ar to e(pi g), so the considered effect develops when weak-localizatio n corrections are still small. The T-c(g, b) dependence at b < b(c) is found. These results are valid at sufficiently large g, whereas a dec rease of g is expected to lead eventually to another b(c)(g) dependenc e, In b(c)/d similar to root g. (C) 1998 Elsevier Science B.V. All rig hts reserved.