The origin of chirality induced spin selectivity in photo-induced electron transfer

TL;DR

This paper proposes a mechanism explaining how spin polarization arises in chiral molecules during photo-induced electron transfer, emphasizing the role of incoherent hopping and spin-orbit interactions, with implications for biological spin transport.

Contribution

It introduces a new theoretical model for chirality-induced spin selectivity in incoherent charge transport, validated by quantum simulations.

Findings

Predicts a non-monotonic temperature dependence of spin polarization

Validates the mechanism with quantum master equations and hierarchical equations of motion

Suggests broad applicability to chiral systems and biological environments

Abstract

Here we propose a mechanism by which spin polarization can be generated dynamically in chiral molecular systems undergoing photo-induced electron transfer. The proposed mechanism explains how spin polarization emerges in systems where charge transport is dominated by incoherent hopping, mediated by spin orbit and electronic exchange couplings through an intermediate charge transfer state. We derive a simple expression for the spin polarization that predicts a non-monotonic temperature dependence consistent with recent experiments. We validate this theory using approximate quantum master equations and the numerically exact hierarchical equations of motion. The proposed mechanism of chirality induced spin selectivity should apply to many chiral systems, and the ideas presented here have implications for the study of spin transport at temperatures relevant to biology, and provide simple principles for the molecular control of spins in fluctuating environments.