All-electrical production of spin-polarized currents in carbon nanotubes: Rashba spin-orbit interaction

TL;DR

This paper investigates how Rashba spin-orbit interaction can generate stable, spin-polarized electrical currents in carbon nanotubes without external magnetic fields, depending on their structural properties.

Contribution

It introduces a detailed analysis of spin-polarized transport in carbon nanotubes considering their chirality and symmetry effects, expanding understanding beyond planar graphene systems.

Findings

Strong spin-polarized currents depend on nanotube diameter, length, and chirality.

Symmetries in spatial and spin variables influence conductance relations.

Stable spin-polarized currents can exist without magnetic fields or impurities.

Abstract

We study the effect of the Rashba spin-orbit interaction in the quantum transport of carbon nanotubes with arbitrary chiralities. For certain spin directions, we find a strong spin-polarized electrical current that depends on the diameter of the tube, the length of the Rashba region and on the tube chirality. Predictions for the spin-dependent conductances are presented for different families of achiral and chiral tubes. We have found that different symmetries acting on spatial and spin variables have to be considered in order to explain the relations between spin-resolved conductances in carbon nanotubes. These symmetries are more general than those employed in planar graphene systems. Our results indicate the possibility of having stable spin-polarized electrical currents in absence of external magnetic fields or magnetic impurities in carbon nanotubes.