Spin polarization driven by molecular vibrations leads to enantioselectivity in chiral molecules.

Abstract

Chirality-induced spin selectivity (CISS) encompasses phenomena such as magnetoresistance and enantiomer separation using ferromagnets. It has recently received notable attention. Despite this growing interest, the microscopic mechanisms driving CISS remain a subject of intense debate. This paper complements and extends the prevailing interpretation that attributes CISS primarily to the electric current in chiral molecules. We propose that molecular vibrations drive spin polarization in chiral molecules and play a critical role in CISS. Our results suggest that magnetic interactions between chiral molecules and ferromagnets, analogous to interlayer exchange coupling, provide a physically consistent mechanism for the observed selectivity. Specifically, we demonstrate that molecular vibrations facilitate the alignment of spin angular momentum dependent on chirality in the presence of an external magnetic field, which is a prerequisite for exchange coupling. These findings necessitate reevaluating spin dynamics, expanding its relevance beyond traditional solid-state physics to fields such as chemical reactions, molecular biology, and drug discovery.