Unusual Spin Polarization in the Chirality Induced Spin Selectivity

Abstract

Chirality-induced spin selectivity (CISS) refers to the fact that electrons get spin polarized after passing through organic chiral molecules in a nanoscale device. In CISS, chiral molecules are commonly believed to be a spin filter through which one favored spin transmits and the opposite spin gets reflected, i.e., transmitted and reflected electrons exhibit opposite spin polarization. In this work, we point out that such a spin filter scenario contradicts the principle that equilibrium spin current must vanish. Instead, we find that both transmitted and reflected electrons present the same type spin polarization, which is actually ubiquitous for a two-terminal device. More accurately, chiral molecules play the role of a spin polarizer rather than a spin filter. The direction of spin polarization is determined by the molecule chirality and the electron incident direction. And the magnitude of spin polarization replies on local spin-orbit coupling in the device. Our work brings a deeper understanding on CISS and interprets recent experiments, for example, the CISS-driven anomalous Hall effect.

arXiv comment5 figures and supplementary information included

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• Spin-dependent Destructive Quantum Interference Associated with Chirality-induced Spin Selectivity in Circular Single Helix Molecules
• Dynamical simulation of chiral induced spin-polarization and magnetization
• Giant chirality-induced spin polarization in twisted transition metal dichalcogenides
• Achiral dipoles on a ferromagnet can affect its magnetization direction
• Should it really be that hard to model the chirality induced spin selectivity effect?
• Mind the Gap: From Resolving Theoretical Foundations of Chiral(ity)-Induced Spin Selectivity to Pioneering Implementations in Quantum Sensing
• Spin conductances and magnetization production in chiral molecular junctions
• First-Principles Analysis of Chirality-Induced Spin Selectivity at Molecule-Metal Interfaces in Photoemission