Weak antilocalization in InAs quantum wires

We study the spin-orbit interaction in diffusive InAs quantum wires ranging from 4 to 0.4 μm in width by means of weak antilocalization (WAL) analysis. Our experimental data can be well fitted using the 2D model, the 1D model and a newly developed dimensional crossover model. However, the physics behind these models is quite different. The 1D and DC models take the wire width into account and show a width-independent spin-orbit interaction, in contrast to the 2D model which incorrectly shows an increase of the spin-orbit interaction with decreasing width. Our experimental data qualitatively agrees with the predicted decrease of the WAL peak amplitude as the wire becomes narrower than the spin-orbit length. However, this effect is not accompanied by the expected suppression of the extracted spin-orbit interaction, obtained from the ID and the crossover model.