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.

Evidence of improvement in thermoelectric parameters of n-type Bi2Te3/graphite nanocomposite

“…For electronic contributions to the heat conductance, Ke of a single 1D channel, the following expression can be derived for ballistic electron transport in the case 1 1 B FE kT −  : [56][57][58] ( ) ( )…”

Anomalies in one-dimensional electron transport: quantum point contacts and wires

“…Of immediate relevance are the conductance steps covering the larger part of the inter-band region up to the onset of the next sub-band. Unlike the '0.7' features [22], they are robustly regular with a systematic dependence on source-drain voltage. We stress the critical conceptual significance of the remarkable, nonlinear 1D conductance steps as revealed by measurements:…”

“…Although this feature manifests primarily in III-V structures, it has been speculated that the effect is in fact generic to all 1D conductors. It has been pointed out [22], that the values actually reported in the literature lie anywhere between 0.2 to 0.8 units of G 0 . To the extent that any theory for the '0.7' effect has been put forward, it has come in two competing forms: spontaneous spin polarization of a 1D electron fluid, or else an induced Kondolike impurity effect.…”

“…A type of non-integer conductance anomaly was eventually observed in 1D channels: the fractional or so-called '0.7' anomaly; a much discussed phenomenon [22]. Although this feature manifests primarily in III-V structures, it has been speculated that the effect is in fact generic to all 1D conductors.…”

Anomalous conductance quantization in the inter-band gap of a one-dimensional channel

“…We focus, by contrast, upon the conductance plateaux extending over the larger part of the inter-band region up to the threshold of the first excited sub-band. Unlike the "0.7" features [14], they are robustly regular with a highly systematic dependence on the source-drain driving voltage.…”