1D diffusion: A novel transport regime in narrow 2DEG channels

Abstract

The transport properties of a two-dimensional electron gas (2DEG) in a narrow electron channel were studied as a function of magnetic field and electron current. When the channel width is smaller than the electron mean free path the non-linear resistance as a function of electron current has been interpreted in terms of Knudsen and Poiseuille transport regimes, in analogy to the molecular flow of gas atoms in a tube. However, a positive magneto-resistance is observed in an electron temperature range beyond the Knudsen regime which contradicts expected Poiseuille transport characteristics. We can trace this unexpected behaviour to the nature of electron-electron scattering processes in a system of reduced dimensionality. The character of the transport in this new regime can be viewed as a one-dimensional (1d) diffusion caused by the interplay of the two most dominant electron scattering processes in a 2DEG. © 2002 Elsevier Science B.V. All rights reserved.