Li Xiaopeng, Nan Jue, Pan Xiangcheng
State Key Laboratory of Surface Physics, Institute of Nanoelectronics and Quantum Computing, and Department of Physics, Fudan University, Shanghai 200438, China.
Shanghai Qi Zhi Institute, AI Tower, Xuhui District, Shanghai 200232, China.
Phys Rev Lett. 2020 Dec 31;125(26):263002. doi: 10.1103/PhysRevLett.125.263002.
Chiral induced spin selectivity (CISS) describes efficient spin filtering by chiral molecules. This phenomenon has led to nanoscale manipulation of quantum spins with promising applications to spintronics and quantum computing, since its discovery nearly two decades ago. However, its underlying mechanism still remains mysterious for the required spin-orbit interaction (SOI) strength is unexpectedly large. Here we report a multi-orbital theory for CISS, where an effective SOI emerges from spontaneous formation of electron-hole pairing caused by many-body correlation. This mechanism produces a strong SOI reaching the energy scale of room temperature, which could support the large spin polarization observed in CISS. One central ingredient of our theory is the Wannier functions of the valence and conduction bands correspond, respectively, to one- and two-dimensional representation of the spatial rotation symmetry around the molecule elongation direction. The induced SOI strength is found to decrease when the band gap increases. Our theory may provide important guidance for searching other molecules with CISS effects.
手性诱导自旋选择性（CISS）描述了手性分子的高效自旋过滤。自近二十年前发现这一现象以来，它已导致对量子自旋的纳米级操控，并有望应用于自旋电子学和量子计算。然而，由于所需的自旋轨道相互作用（SOI）强度出乎意料地大，其潜在机制仍然神秘。在此，我们报告了一种关于CISS的多轨道理论，其中有效的SOI源自多体关联导致的电子 - 空穴对的自发形成。这种机制产生了一个强大的SOI，达到室温的能量尺度，这可以支持在CISS中观察到的大自旋极化。我们理论的一个核心要素是价带和导带的万尼尔函数分别对应于围绕分子伸长方向的空间旋转对称性的一维和二维表示。发现当带隙增加时，诱导的SOI强度会降低。我们的理论可能为寻找其他具有CISS效应的分子提供重要指导。
