Chirality-induced spin selectivity (CISS) generates spin-polarized currents in nonmagnetic materials from structural chirality alone, yet its microscopic origin remains debated. Using a first-principles spatiotemporal density-matrix dynamics approach including electron-phonon scatterings with self-consistent spin-orbit coupling (SOC), we elucidate the interplay of SOC, structural chirality, and spin-dependent electron-phonon interactions in driving the generation and transport of spin and orbital angular momentum. In particular we quantitatively distinguish CISS from the collinear Edelstein effect (CEE) in trigonal selenium, a prototypical chiral solid. CEE yields a spatially uniform spin polarization scaling linearly with applied field (Sz∝E). In contrast, explicit spin-dependent electron-phonon scattering produces a nonlinear response (Sz∝E2) and a length-dependent spin accumulation -- the hallmark experimental signature of CISS. We identify intervalley scattering mediated by chiral phonon angular momentum as the microscopic origin of this nonlinearity.
@article{arxiv.2508.03886,
title = {Chirality-Induced Spin Selectivity: Nonlinear Spin Response from Electron-Phonon Scattering},
author = {Mayank Gupta and Andrew Grieder and Mayada Fadel and Jacopo Simoni and Junting Yu and Ravishankar Sundararaman and Yuan Ping},
journal= {arXiv preprint arXiv:2508.03886},
year = {2026}
}