Spin Filtering through Single-Wall Carbon Nanotubes Functionalized with Single-Stranded DNA

TL;DR

This study demonstrates that single-walled carbon nanotubes functionalized with single-stranded DNA can act as highly effective spin filters, achieving up to 74% spin polarization, which surpasses traditional ferromagnetic materials and opens new avenues in organic spintronics.

Contribution

The paper provides experimental evidence that ssDNA-wrapped SWCNTs function as efficient spin filters with high polarization, supported by magnetoresistance measurements and theoretical consistency.

Findings

Achieved up to 74% spin polarization at low temperatures.

Demonstrated spin filtering surpassing traditional ferromagnetic materials.

Linked helicoidal potential of ssDNA to Rashba spin-orbit interaction.

Abstract

High spin polarization materials or spin filters are key components in spintronics, a niche subfield of electronics where carrier spins play a functional role. Carrier transmission through these materials is "spin selective" i.e. these materials are able to discriminate between "up" and "down" spins. Common spin filters include transition metal ferromagnets and their alloys, with typical spin selectivity (or, polarization) ~50% or less. Here we consider carrier transport in an archetypical one-dimensional molecular hybrid in which a single wall carbon nanotube (SWCNT) is wrapped around by single stranded deoxyribonucleic acid (ssDNA). By magnetoresistance measurements we show that this system can act as a spin filter with maximum spin polarization approaching ~74% at low temperatures, significantly larger than transition metals under comparable conditions. Inversion asymmetric helicoidal potential of the charged ssDNA backbone induces a Rashba spin-orbit interaction in the SWCNT channel and polarizes carrier spins. Our results are consistent with recent theoretical work that predicted spin dependent conductance in ssDNA-SWCNT hybrid. Ability to generate highly spin polarized carriers using molecular functionalization can lead to magnet-less and contact-less spintronic devices in the future. This can eliminate the conductivity mismatch problem and open new directions for research in organic spintronics.