The role of orbital polarization and spin-dependent electron-phonon scatterings in chiral-induced spin selectivity

Chiral materials exhibit unique spin and charge transport properties, notably through the chiral induced spin selectivity (CISS) effect, enabling spin-polarized currents in nonmagnetic materials. In this study, we investigate the microscopic mechanisms underlying CISS in trigonal Se, based on a first principles spatial-temporal density-matrix dynamics approach, including electron-phonon scattering with self-consistent spin-orbit couplings (SOC) [1]. Our approach elucidates the interplay of SOC, structural chirality, and spin-dependent electron-phonon interactions in driving the generation and transport of spin and orbital angular momentum. We demonstrate that charge transport along the chiral axis induces significant chirality-dependent spin and orbital polarization, which increases monotonically with increasing chirality. We show the orbital polarization generated in CISS has a weak dependence on SOC, unlike spin. Most importantly, we reveal the key difference between the CISS and colinear Edelstein effect originating from spin-dependent electron-phonon scatterings, which explains the spin polarization increase with device lengths, a unique feature in CISS [2]. 

[1] J Simoni et al., First-principles open quantum dynamics for solids based on density-matrix formalism, J. Chem. Physics, (2025) arXiv2504.17936.

[2] M. Gupta et al., The role of orbital polarization and spin-dependent electron-phonon scatterings in chiral-induced spin selectivity, (2025) arXiv:2508.03886.