Conductance behavior in nanowires with spin-orbit interaction -- A numerical study

TL;DR

This study numerically investigates conductance in semiconducting nanowires with spin-orbit interaction, revealing how potential profiles and disorder influence the ability to detect SOI effects through transport measurements.

Contribution

It identifies optimal conditions for observing spin-orbit interaction signatures in nanowire conductance, considering realistic effects like disorder and potential smoothness.

Findings

Smooth potential profiles can mask SOI effects in conductance.

Optimal potential regimes enhance visibility of SOI signatures.

Disorder and temperature effects can obscure SOI signals, but optimal conditions mitigate this.

Abstract

We consider electronic transport through semiconducting nanowires (W) with spin-orbit interaction (SOI), in a hybrid N-W-N setup where the wire is contacted by normal-metal leads (N). We investigate the conductance behavior of the system as a function of gate and bias voltage, magnetic field, wire length, temperature, and disorder. The transport calculations are performed numerically and are based on standard recursive Green's function techniques. In particular, we are interested in understanding if and how it is possible to deduce the strength of the SOI from the transport behavior. This is a very relevant question since so far no clear experimental observation in that direction has been produced. We find that the smoothness of the electrostatic potential profile between the contacts and the wire plays a crucial role, and we show that in realistic regimes the N-W-N setup may mask the effects of SOI, and a trivial behavior with apparent vanishing SOI is observed. We identify an optimal parameter regime, with neither too smooth nor too abrupt potentials, where the signature of SOI is best visible, with and without Fabry-Perot oscillations, and is most resilient to disorder and temperature effects.