AI 中文总结
该研究揭示具有离散螺旋对称的分子可通过准动量处强自旋分离增强自旋保持，其自旋保真度与CISS一致，经紧束缚模型验证，且在自旋阀装置中呈现对称保护自旋保真度的磁阻特征。
AI 中文摘要
在长分子的电子输运中，仅当停留时间远小于特征自旋混合时间尺度ℏ/Δ时，自旋才有望被保持，其中Δ是自旋相关势的大小，例如自旋轨道耦合。我们表明，在具有离散螺旋对称的分子中，由于准动量处的强自旋分离，自旋保持可远超出该时间尺度得到增强。长分子中的这种自旋保真度与手性诱导自旋选择性（CISS）一致，表明长手性分子中存在自旋相关输运，且具有放大的自旋分裂机制。我们对增强的自旋保持进行了解析推导，并在紧束缚模型上进行了测试，结果证实当螺旋对称被破坏或从离散变为连续时，该效应会逐渐减弱。此外，我们开展了输运模拟，表明在带有两个磁性电极的自旋阀装置中会出现对称保护自旋保真度的强磁阻痕迹，我们将此作为可通过实验获取的特征。
英文摘要
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.
Comments10 pages, 5 figures
