Experiments on strongly interacting two-dimensional systems and the metal-insulator transition

Abstract

In 1994 the belief that all two-dimensional systems are insulating at T = 0 was challenged by the interpretation of experiments on high-mobility Si-MOSFETs [148]. In these samples resistivities continuously decreasing with decreasing temperature have been observed for certain electron densities and interpreted as an indication for a metallic ground state at T = 0. Lowering the electron density leads to an increasing resistivity with decreasing temperature as expected in the strongly localized (hopping) transport regime. It was suggested that the transition between the metallic and the insulating range of densities might be an interaction-driven quantum phase transition [148–150] (see [151, 152] for a simple account of quantum phase transitions, [153] for a review) from then on called the “metal-insulator transition in two dimensions at zero magnetic field.” Such a metal-insulator transition would require a serious modification of the one-parameter scaling theory of localization in the sense that the scaling function β(g) should have at least one zero. A possible scenario is indicated in Fig. 4.1 as a dashed line. Another scenario would replace the one-parameter scaling function β(g) bv a scaling function with more parameters.KeywordsCarrier DensityGate VoltageQuantum Phase TransitionMetallic BehaviorWeak LocalizationThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.