Analysis of the temperature-dependent quantum pointcontact conductance in relation to the metal-insulator transition intwo dimensions

Abstract

The temperature dependence of the conductance of a quantum pointcontact has been measured. The conductance as a function of theFermi energy shows temperature-independent fixed points, located atroughly multiple integers of e2/h. Around the first fixedpoint at e2/h, the experimental data for different temperaturescan be scaled onto a single curve. For pure thermal smearing of theconductance steps, a scaling parameter of one is expected. Themeasured scaling parameter, however, is significantly larger than 1.The deviations are interpreted as a signature of the potentiallandscape of the quantum point contact, and of the source-drainbias voltage. We relate our results phenomenologically to themetal-insulator transition in two dimensions.