Year: 2026
Type: preprint
Abstract: In electronic transport through long molecules, spin is expected to be preserved only when the dwell time is much shorter than the characteristic spin-mixing timescale $\hbar/Δ$, where $Δ$ is the magnitude of a spin-dependent potential, such as spin-orbit coupling. We show that, in molecules featuring discrete screw symmetry, spin preservation can be enhanced far beyond this timescale owing to strong spin separation in quasi-momentum. This spin fidelity in long molecules is consistent with chirality-induced spin selectivity (CISS), suggesting spin-dependent transport in long, chiral molecules with amplified spin-splitting mechanisms. We provide analytical derivation of the enhanced spin preservation and test it on tight-binding models, which confirm that the effect gradually weakens when the screw symmetry is broken or changes from discrete to continuous. Furthermore, we perform transport simulations to show that a strong magnetoresistance trace of symmetry-protected spin fidelity emerges in a spin-valve setup with two magnetic leads, which we propose as an experimentally accessible signature.
Source: arXiv (Cornell University)
Institution: Freie Universität Berlin
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funder: Deutsche Forschungsgemeinschaft
OpenAlex ID: W7204542739
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