An analytic model of chiral-induced spin selectivity

Abstract: Organic materials are known to feature long spin-diffusion times, originating in a generally small spin-orbit coupling observed in these systems. From that perspective, chiral molecules acting as efficient spin selectors pose a puzzle, that attracted a lot of attention during the recent years. Here we revisit the physical origins of chiral-induced spin selectivity (CISS), and propose a simple analytic minimal model to describe it. The model treats a chiral molecule as an anisotropic wire with molecular dipole moments aligned arbitrarily with respect to the wire's axes, and is therefore quite general. Importantly, it shows that helical structure of the molecule is not necessary to observe CISS and other chiral non-helical molecules can also be considered as a potential candidates for CISS effect. We also show that the suggested simple model captures the main characteristics of CISS observed in experiment, without the need for additional constraints employed in the previous studies. The results pave the way for understanding other related physical phenomena where CISS effect plays an essential role.