Dalum Sakse, Hedegård Per
Niels Bohr Institute , University of Copenhagen , Copenhagen DK-2100 , Denmark.
Sino-Danish Center for Education and Research (SDC), Eastern Yanqihu Campus , University of Chinese Academy of Sciences , Huaibeizhen, Huairou Qu, Beijing 101408 , China.
Nano Lett. 2019 Aug 14;19(8):5253-5259. doi: 10.1021/acs.nanolett.9b01707. Epub 2019 Jul 10.
A general theory of the chiral induced spin selectivity (CISS) effect is presented. It is based on the fact that the spin-orbit (SO) coupling is small, a few meV, for the light atoms, which make up typical chiral molecules in experiments. We present a theorem based on the Onsager reciprocal principle, which states that the CISS effect vanishes when thermally averaging over all electron states. This zero result is avoided by the very nonthermal character of the incoming optically generated electrons in experimental realizations. Despite the small SO-coupling, the presence of accidental degeneracies in the molecular spectrum yields a sizable spin polarization. The CISS effect in the presence of magnetic leads is special. We prove that, in a situation with one magnetic lead, the other lead will become magnetized. This results from the interplay between the spin-orbit coupling in the chiral molecule and the magnetized lead. Numerical calculations for realistic chiral molecules confirm the theory.
本文提出了一种手性诱导自旋选择性（CISS）效应的通用理论。该理论基于这样一个事实：对于构成实验中典型手性分子的轻原子，其自旋轨道（SO）耦合很小，只有几毫电子伏特。我们基于昂萨格互易原理提出了一个定理，该定理表明，当对所有电子态进行热平均时，CISS效应消失。在实验实现中，由于入射光生电子具有非常非热的特性，从而避免了这个零结果。尽管SO耦合很小，但分子光谱中偶然简并的存在会产生相当大的自旋极化。存在磁性引线时的CISS效应很特殊。我们证明，在存在一个磁性引线的情况下，另一个引线会被磁化。这是由手性分子中的自旋轨道耦合与磁化引线之间的相互作用导致的。对实际手性分子的数值计算证实了该理论。
