Metal-insulator transition in 2D: the role of interactions and disorder

Abstract

We present a model for the metal-insulator transition in 2D, observed in the recent years. Our starting point consists of two ingredients only, which are ubiquitous in the experiments: Coulomb interactions and weak disorder spin-orbit scattering (coming from the interfaces of the heterostructures in question). In a diagramatic approach, we predict the existence of a characteristic temperature $T_o=T_o(n,\omega_H)$, $n$ being the density of carriers, and $\omega_H$ the Zeeman energy, below which these systems become metallic. This is in very good agreement with experiments, and corroborates the fact that varying $n$ and $\omega_H$ are equivalent ways into/out of the metallic regime. The resistivity, calculated as a function of temperature and $\om_H$ in the metallic state, compares favorably to experiment. We comment on the nature of the transition, and calculate the specific heat of the system.