Conductance anomalies in quantum point contacts and 1D wires

Abstract

Over the last decade, interest in 1D charge transport has progressed from the seminal discovery of Landauer quantization of conductance, as a function of carrier density, to finerscale phenomena at the onset of quantization. This has come to be called the '0.7 anomaly', rather connoting a theoretical mystery of some profundity and universality, which remains open to date. Its somewhat imaginative appellation may tend to mislead, since the anomaly manifests itself over a range of conductance values: anywhere between 0.25-0.95 Landauer quanta. In this paper we offer a critique of the 0.7 anomaly and discuss the extent to which it represents a deep question of physics.