Persistent Chirality-Induced Spin-Selectivity Effect in Circular Helix Molecules

Abstract

The spin−orbit coupling (SOC), the dynamics of the nonequilibrium transport process, and the breaking of time-reversal and space-inversion symmetries have been regarded as key factors for the emergence of chirality-induced spin selectivity (CISS) and chiralitydependent spin currents in helix molecules. In this work, we demonstrated the generation of persistent CISS currents in various circular single-stranded DNAs and 3 10 -helix proteins for the first time, regardless of whether an external magnetic flux is applied or not. This new CISS effect presents only in equilibrium transport processes, distinct from the traditional CISS observed in nonequilibrium transport processes and linear helix molecules; we term it as the PCISS effect. Notably, PCISS manifests irrespective of whether the SOC is chirality-driven or stems from heavy-metal substrates, making it an efficient way to generate chirality-locked pure spin currents. Our research establishes a novel paradigm for examining the underlying physics of the CISS effect.

Spin-Charge Conversion in Chiral Polymers with Hopping Conduction

“…The decisive role of three-site hops in disordered systems was first pointed out by Holstein in describing the Hall effect and subsequently found to be critical in the hopping spin Hall effect . It is remarkable that the extra phase in eq , A ijk z σ z /4 L 2 , is entirely geometric (Berry phase), independent of other material properties, interactions, and external fields, compared to other Berry phases previously invoked to describe possible persistent currents and to explain the strong spin selectivity in chiral polymer chains . Since electron hopping probability decays exponentially over distance, the most important triads are those formed by neighboring sites, whose orientations are dictated by the polymer’s chirality, as shown in Figure .…”