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

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.