One-dimensional extended states in partially disordered planar systems

We obtain analytically a continuum of one-dimensional ballistic extended st ates in a two-dimensional disordered system, which consists of compactly co upled random and pure square lattices. The extended states give a marginal metallic phase with finite conductivity sigma(0) = 2e(2)/h in a wide energy range, whose boundaries define the mobility edges of a first-order metal-i nsulator transition. We show current-voltage duality, H-parallel to/T scali ng of the conductivity in a parallel magnetic field H-parallel to and non-F ermi liquid properties when long-range electron-electron interactions are i ncluded. (C) 1999 Elsevier Science B.V.