Chirality-induced spin filtering in pseudo Jahn-Teller molecules
Chirality-induced spin filtering in pseudo Jahn-Teller molecules
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DOI：
10.1103/physrevb.105.195117
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发表时间：
2021-11
影响因子：
3.7
通讯作者：
Akihito Kato;H. Yamamoto;J. Kishine
中科院分区：
文献类型：
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作者：
Akihito Kato;H. Yamamoto;J. Kishine
手性诱导的自旋选择性（CISS）是指诱导通过手性材料传输的电子的自旋极化的能力。一个重要的实验观察是，即使对于具有弱自旋轨道耦合（SOC）的有机分子，在室温下也实现了令人难以置信的大自旋极化，尽管SOC是唯一可以在设置中操纵电子自旋的相互作用。因此，CISS的机制需要以对SOC强度的大小不敏感或增强SOC强度的大小的方式来构造。在本文中，我们描述了一个模型的手性分子，属于点群C3的CISS的理论研究。在这个分子中，电子的平移和旋转自由度的注入电子是通过与伪Jahn-Teller效应的核振动模式相互耦合。通过适当地考虑分子的对称性以及时间反演对称性，并根据分子的角动量和自旋动量量子数对分子基态进行分类，我们证明了手性分子可以充当有效的自旋过滤器。在该模型中，自旋过滤效率几乎不依赖于SOC强度，而自旋过滤效率远远超过了仅依赖于SOC的自旋极化率。结果表明，核振动不仅起到介导自旋-转动耦合的作用，而且还提高了自旋过滤效率。
Chirality-induced spin selectivity (CISS) refers to an ability to induce a spin polarization of an electron transmitted through chiral materials. An important experimental observation is that incredibly large spin polarization is realized at room temperature even for organic molecules that have weak spin-orbit coupling (SOC), although SOC is the only interaction that can manipulate the electrons’ spins in the setups. Therefore, the mechanism of the CISS needs to be constructed in a way insensitive to or enhancing the magnitude of the SOC strength. In this paper, we describe a theoretical study of CISS with a model chiral molecule that belongs to the point group C 3 . In this molecule, electronic translational and rotational degrees of freedom for an injected electron are coupled to one another via the nuclear vibrational mode with a pseudo Jahn-Teller effect. By properly taking the molecular symmetry as well as the time-reversal symmetry into account and classifying the molecular ground states by their angular- and spin-momentum quantum numbers, we show that the chiral molecule can act as an efficient spin filter. The efficiency of this spin filtering can be nearly independent of the SOC strength in this model, while it well exceeds the spin polarization relying solely on the SOC. The nuclear vibrations turned out to have the role of not only mediating the translation-rotation coupling, but also enhancing the spin-filtering efficiency.