Chirality-induced spin selectivity of graphene chiral superstructures and their true/false chirality of electron motion

“Chiral-induced spin selectivity (CISS)” and its device applications are predominantly at the experimental stage, with mechanisms not fully understood. There is a need for new chiral materials with simple structures and high room-temperature electron spin polarization rates, crucial for theoretical studies and low-power spin optoelectronic devices. This study examines the CISS effect in carbon nanotubes, graphene chiral rolls, and graphene chiral stacks. While all three exhibit chirality, only the one-side follow curved surface of the graphene rolls demonstrates the CISS effect. Using true and false chirality analysis from Professor Barron, we found that only the charge motion (current) on the chiral surface is true chiral, leading to spin polarization. Thus, the CISS phenomenon occurs when charge motion on the chiral surface is chiral. Both chiral surface structures and chiral charge motion are necessary for electron spin polarization. Further theoretical validation of these conditions will enhance CISS theory.