Spin filtering with poly-T wrapped single wall carbon nanotubes.

Abstract

Spin filtering is an essential operation in spintronics that allows the creation and detection of spin polarized carriers. Transition metal ferromagnets are used as spin filters in most cases, though their spin filtering efficiency is only around ∼50%, thereby limiting the efficiency of spintronic devices. Recently, chiral systems such as DNA have been shown to exhibit efficient spin filtering, a phenomenon often dubbed as "chirality induced spin selectivity" (CISS). In this work, we consider single wall carbon nanotubes helically wrapped with single stranded poly-T DNA. By magnetoresistance measurements we show that this system exhibits significant spin polarization of ∼80%, which could be attributed to the Rashba spin-orbit interaction induced by the inversion-asymmetric helical potential of the DNA. The observed spin polarization is larger than that reported before for d(GT)15 strands. Such systems allow tailoring of spin polarization by chemical means and also allow extremely localized creation and detection of spin polarization without any magnetic element and could lead to extreme miniaturization and compact integration of spintronic devices and circuits.