Spin-selective transport through chiral ferromagnetic nanohelices.

Chiral crystals with well-defined handedness in atomic arrangements exhibit properties such as spin selectivity, asymmetric magnetoresistance, and skyrmions. Although similar geometry-induced phenomena in chiral organic molecule-based systems were observed, synthesizing uniform inorganic nanostructures with desired chirality using a scalable method remains challenging. We electrochemically synthesized chiral ferromagnetic cobalt-iron nanohelices from nanoparticles in anodized aluminum oxide templates. The spiral directions and the number of strands were regulated by incorporating chiral molecules and applying an appropriate potential. We demonstrate the observation of Faraday's law of induction at the nanoscale and show how chiral nanohelices regulate the electron flow direction. The implications of our findings extend to the technological realm, with chirality- and ferromagnetism-based spin-tunable devices. Editor's summary: Chiral nanohelices electrochemically synthesized from cobalt-iron nanoparticles can act as spin filters when aligned on magnetic substrates. Jeon et al. used chiral organic molecules and applied potentials to control the spiral direction and strand pitch during assembly in anodized aluminum oxide templates. Different handed helices showed opposite signs of electromotive force induction, and this effect served as a metric for chirality. —Phil Szuromi [ABSTRACT FROM AUTHOR]