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Transmission Eigenvalues in Chiral Molecular Junctions
Ulrich Pototschnig1, Sumit Naskar1,2, Thorsten Hansen3
1Department of Chemistry, Universität Hamburg, HARBOR Bldg. 610, Luruper Chaussee 149, 22761 Hamburg, Germany.
ACS Omega
|July 24, 2026
Summary
Chiral-induced spin selectivity (CISS) in molecular junctions depends on transmission eigenvalues. Realistic systems show multiple eigenvalues, influencing CISS effects and suggesting new experimental avenues for studying spin selectivity.
Area of Science:
- Condensed Matter Physics
- Molecular Electronics
- Quantum Chemistry
Background:
- Chiral-induced spin selectivity (CISS) arises from the interaction between molecular chirality and electron spin. This phenomenon is observed in magnetoresistance measurements of two-terminal chiral junctions.
- Existing theoretical models often simplify chiral junctions to one-dimensional systems or idealized helices, prompting investigation into more realistic molecular geometries.
Purpose of the Study:
- To investigate the electron transport characteristics of realistic chiral molecular junctions.
- To evaluate the influence of non-idealized system properties, specifically the number of transmission eigenvalues, on the CISS effect.
Main Methods:
- Focus on the number of nonzero transmission eigenvalues as a metric for deviation from idealized models.
- Computational analysis of electron transport in various chiral molecular junctions, including helicenes and peptides with different anchoring groups.
Main Results:
- All considered realistic chiral molecular systems exhibited at least two transmission eigenvalues above the noise threshold.
- The prominence of these eigenvalues varied, being most pronounced in unsubstituted [6]-helicene, thio-[6]-helicene, [6]-carboxyhelicene, and a pentapeptide α-helix with thiolated terminals.
Conclusions:
- The presence of multiple significant transmission eigenvalues in realistic chiral junctions is a key factor influencing CISS.
- Comparative experimental studies focusing on molecules with varying transmission eigenvalue characteristics are proposed to further elucidate the CISS mechanism.
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