On the Nature of the Metal-Insulator Transition in Metal-Rare-Gas Mixture Films

Abstract

The nature of the metal-insulator (MI) transition in frozen metal-rare-gas mixtures has been the subject of extensive research in recent years.1–9 Two different types of MI transition can occur in such mixtures: (1) the classical percolation transition, typical for granular systems and (2) the Anderson or Anderson-Mott transition due to localization in disordered systems. One can distinguish between these two types of MI transition by measuring the electrical do conductivity G as a function of metal atomic concentration x. For both transitions the conductivity at T=0 K starts at the critical metal atomic concentration xc and develops continuosly according to a power-law G α (x-xc)v. The characteristic exponent V as predicted by theory, however, is different for these two types of MI transition. For the classical percolation transition V= 1.7 – 2.0,10,11 while a value between 1.0 and 0.5 is predicted for an Anderson or Anderson-Mott transition. 12-15