A group-theoretic approach to the origin of chirality-induced spin selectivity in non-magnetic molecular junctions

Abstract

Spin-orbit coupling gives rise to a range of spin-charge interconversion phenomena in non-magnetic systems where certain spatial symmetries are reduced or absent. Chirality-induced spin selectivity (CISS), a term that generically refers to a spin-dependent electron transfer in non-magnetic chiral systems, is one such case, appearing in a variety of seemingly unrelated situations ranging from inorganic materials to molecular devices. In particular, the origin of CISS in molecular junctions is a matter of an intense current debate. Here we derive a set of geometrical conditions for this effect to appear, hinting at the fundamental role of symmetries beyond otherwise relevant quantitative issues. Our approach, which draws on the use of point-group symmetries within the scattering formalism for transport, shows that electrode symmetries are as important as those of the molecule when it comes to the emergence of a spin-polarization and, by extension, to the possible appearance of CISS. It turns out that standalone metallic nanocontacts can exhibit spin-polarization when relative rotations which reduce the symmetry are introduced. As a corollary, molecular junctions with $\text{achiral}$ molecules can also exhibit spin-polarization along the direction of transport, provided that the whole junction is chiral in a specific way. This formalism also allows the prediction of qualitative changes of the spin-polarization upon substitution of a chiral molecule in the junction with its enantiomeric partner. Quantum transport calculations based on density functional theory corroborate all of our predictions and provide further quantitative insight within the single-particle framework.

34 pages, 4 figures, 1 table

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Cited by in corpus (5)

• Spin-dependent Destructive Quantum Interference Associated with Chirality-induced Spin Selectivity in Circular Single Helix Molecules
• Building unconventional magnetic phases on graphene by H atom manipulation: From altermagnets to Lieb ferrimagnets
• Giant chirality-induced spin polarization in twisted transition metal dichalcogenides
• Mind the Gap: From Resolving Theoretical Foundations of Chiral(ity)-Induced Spin Selectivity to Pioneering Implementations in Quantum Sensing
• Probing the Chirality of Trigonal Selenium and Tellurium by Spin and Orbital Hall Effects