Unraveling the origin of the chirality-induced spin-selectivity effect

Zoom: https://us02web.zoom.us/j/89236785442

When electrons are injected through a chiral molecule, the resulting current may become spin polarized. This effect, known as the chirality-induced spin-selectivity (CISS) effect, has been suggested to emerge due to the interplay between spin–orbit interactions and the chirality within the molecule. However, such explanations require unrealistically large values for the molecular spin–orbit interaction without any physical justification. Put simply, to date, the physical origin of  the CISS effect is unknown. 
Here, we present a theory for the CISS effect based on the interplay between spin–orbit interactions in the electrode, the chirality of the molecule (which induces a solenoid field), and spin-transfer torque at the molecule–electrode interface. Using a mean-field calculation with simple models for the molecular junction, we show that our phenomenological theory can qualitatively account for all key experimental observations, most importantly the magnitude of the CISS with realistic parameters. We also provide a set of predictions which can be readily tested experimentally, and show recent data to corroborate these predictions. 

S. Alwan & Y. Dubi, J. Am. Chem. Soc. 2021, 143, 35, 14235–14241.