Rashba spin orbit interaction in a quantum wire superlattice

TL;DR

This paper investigates how Rashba spin-orbit interaction influences energy gaps and conductance in a quantum wire superlattice, demonstrating control over band gaps and proposing a conductance-based method to measure Rashba coupling strength.

Contribution

It reveals the shift of energy gaps due to Rashba interaction and introduces a way to determine Rashba strength through conductance measurements.

Findings

Energy gaps are shifted from Bragg planes by Rashba interaction.

Conductance dips correspond to energy gaps in the superlattice.

Rashba strength can be inferred from conductance measurements.

Abstract

In this work we study the effects of a longitudinal periodic potential on a parabolic quantum wire defined in a two-dimensional electron gas with Rashba spin-orbit interaction. For an infinite wire superlattice we find, by direct diagonalization, that the energy gaps are shifted away from the usual Bragg planes due to the Rashba spin-orbit interaction. Interestingly, our results show that the location of the band gaps in energy can be controlled via the strength of the Rashba spin-orbit interaction. We have also calculated the charge conductance through a periodic potential of a finite length via the non-equilibrium Green's function method combined with the Landauer formalism. We find dips in the conductance that correspond well to the energy gaps of the infinite wire superlattice. From the infinite wire energy dispersion, we derive an equation relating the location of the conductance dips as a function of the (gate controllable) Fermi energy to the Rashba spin-orbit coupling strength. We propose that the strength of the Rashba spin-orbit interaction can be extracted via a charge conductance measurement.