Continuum model for chiral induced spin selectivity in helical molecules,The Journal of Chemical Physics

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Continuum model for chiral induced spin selectivity in helical molecules
The Journal of Chemical Physics ( IF 3.1 ) Pub Date : 2015-05-21 12:15:22 , DOI: 10.1063/1.4921310
Ernesto Medina _{1,

2,

3} , Luis A. González-Arraga ₄ , Daniel Finkelstein-Shapiro ₃ , Bertrand Berche _{1,

2} , Vladimiro Mujica ₃

Affiliation

A minimal model is exactly solved for electron spin transport on a helix. Electron transport is assumed to be supported by well oriented p_z type orbitals on base molecules forming a staircase of definite chirality. In a tight binding interpretation, the spin-orbit coupling (SOC) opens up an effective π_z − π_z coupling via interbase p _x,y − p_z hopping, introducing spin coupled transport. The resulting continuum model spectrum shows two Kramers doublet transport channels with a gap proportional to the SOC. Each doubly degenerate channel satisfies time reversal symmetry; nevertheless, a bias chooses a transport direction and thus selects for spin orientation. The model predicts (i) which spin orientation is selected depending on chirality and bias, (ii) changes in spin preference as a function of input Fermi level and (iii) back-scattering suppression protected by the SO gap. We compute the spin current with a definite helicity and find it to be proportional to the torsion of the chiral structure and the non-adiabatic Aharonov-Anandan phase. To describe room temperature transport, we assume that the total transmission is the result of a product of coherent steps.

中文翻译：

螺旋分子中手性诱导自旋选择性的连续体模型

精确求解了一个最小模型，用于螺旋上的电子自旋传输。假定电子传输由形成明确手性阶梯的基础分子上取向良好的p _z型轨道支持。在紧张的结合解释，自旋-轨道耦合（SOC）开辟了一个有效的π _ž - π _Ž 经由interbase的耦合p _X_，_ÿ - p _ž 跳跃，引入自旋耦合传输。所得的连续谱模型光谱显示了两个Kramers双峰传输通道，其间隙与SOC成正比。每个双简并通道均满足时间反转对称性；然而，偏置选择了传输方向，因此选择了自旋取向。该模型预测（i）根据手性和偏向选择哪种自旋取向，（ii）自旋偏好随输入费米能级变化的变化，以及（iii）受SO间隙保护的反向散射抑制。我们以一定的螺旋度计算自旋电流，发现它与手性结构和非绝热Aharonov-Anandan相的扭转成正比。为了描述室温下的传输，我们假设总传输是连贯步骤的乘积。

更新日期：2015-05-22

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