Spin-current correlations in photoionization of chiral molecules

TL;DR

This paper reveals how chiral molecules support unique spin-momentum correlations in photoionization, explaining phenomena like CISS through conditioned measurements and identifying molecular pseudovectors that govern these effects.

Contribution

It demonstrates the existence of time-even spin correlations in chiral molecule photoionization and links these to the fundamental mechanisms behind CISS phenomena.

Findings

Photoelectron spin is enantio-sensitively locked to current direction.

Molecular spin textures are created by photoionization, quantified by a pseudoscalar.

Photon spin influences triple correlations with electron momentum and spin.

Abstract

Chiral molecular structures enable time-odd pseudotensor that controls correlations between photoelectron spin and molecular orientation in photoionization (arXiv:2505.22433). We show that chiral structures also support time-even correlations between the photoelectron spin and its momentum. Fundamentally, these correlations can only be revealed in conditioned measurements. We argue that conditioned measurements are the sole origin of a broad class of phenomena termed chirality-induced spin selectivity (CISS), because all these phenomena require a correlated detection of the spin and another variable, e.g., electron current. We consider one-photon ionization of an isotropic ensemble of randomly oriented chiral molecules and show that the direction of the resulting photoelectron current is enantio-sensitively `locked' to the photoelectron spin even under isotropic illumination. We also identify molecular frame spin texture created by photoionization in which its flux through the energy shell is the molecular pseudoscalar that quantifies the underlying spin-current correlations. Next, we consider the effect of the photon spin on these correlations and find that chiral structure also leads to triple correlations between the photoelectron momentum, its spin and the photon spin. Our results identify two molecular pseudovectors underlying the full complexity of the multitude of spin-conditioned measurements of the photoelectron current