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 in 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 the helical structure of the molecule is not necessary to observe CISS and other chiral nonhelical molecules can also be considered as potential candidates for the CISS effect. We also show that the suggested simple model captures the main characteristics of CISS observed in the experiment, without the need for additional constraints employed in the previous studies. The results pave the way for understanding other related physical phenomena where the CISS effect plays an essential role.
Bibliographical noteFunding Information:
A.G. is grateful to Artem Volosniev for valuable discussions. A.G. acknowledges support from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 754411. Y.P. acknowledges support from the Volkswagen Foundation (No. VW 88 367) and the Israel Ministry of Science (MOS). M.L. acknowledges support from the Austrian Science Fund (FWF), under project No. P29902-N27, and from the European Research Council (ERC) Starting Grant No. 801770 (ANGULON).
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