Non-Hermitian Exchange as the Origin of Chirality-Induced Spin Selectivity

TL;DR

This paper proposes a new quantum mechanical framework based on non-Hermitian exchange interactions to explain the universal origin of chirality-induced spin selectivity, linking quantum statistics, symmetry breaking, and spin transport.

Contribution

It introduces a novel non-Hermitian exchange mechanism that unifies all CISS effects and connects quantum physics with structural chirality in a comprehensive way.

Findings

Breaking mirror symmetries enforces twin-pair electron exchange.

This exchange violates parity and time-reversal symmetry but preserves PT symmetry.

Chiral quantum states link electron spin and motion, driving spin-momentum locking.

Abstract

For over two decades, the role of structural chirality in spin polarization has been widely investigated, with implications for the origins of life, catalysis, and quantum phenomena. Yet, it remains unclear whether all chirality-induced spin selectivity (CISS) effects arise from a common mechanism. We show that breaking all mirror symmetries in structurally chiral electron systems enforces a twin-pair electron exchange, inherently violating both parity P and time-reversal T symmetry while preserving combined PT-symmetry of the Hamiltonian. This exchange produces chiral quantum states where electron spin and motion are intrinsically linked, a key feature of CISS. At interfaces, these states drive spin and charge accumulation via spin-momentum locking. Our findings establish a new paradigm connecting quantum statistics, non-Hermitian physics, and spin transport with structural chirality. This framework unifies all observed CISS effects and provides guiding principles for designing chiral materials for spintronic and quantum applications.