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arxiv: 2606.30670 · v1 · pith:SG2I6HNCnew · submitted 2026-06-24 · ⚛️ physics.chem-ph · cond-mat.mes-hall

Large CISS Polarization from the Hierarchy Between Transport and Geometrical Spin Currents

Zeev Vager (Weizmann Institute of Science , Rehovot , Israel) This is my paper

Pith reviewed 2026-07-01 07:12 UTC · model grok-4.3

classification ⚛️ physics.chem-ph cond-mat.mes-hall
keywords chiral-induced spin selectivityCISS polarizationgeometrical spin currentdsDNAtransport leakagecurved electron paths
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The pith

Large CISS polarization arises when transport currents act as weak leaks from much stronger pre-existing geometrical spin currents in chiral molecules.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper argues that the large spin polarization seen in chiral-induced spin selectivity experiments cannot be explained by the weak spin-orbit coupling native to organic molecules. Instead it proposes that electrons constrained to the curved paths of a double-stranded DNA molecule support a geometrical spin current whose intrinsic scale is substantially larger than the currents actually measured in transport. Because the observed transport is only a small leakage from these stronger underlying states, the leakage itself can select one spin branch over the other and thereby produce the high polarization without needing any additional amplification mechanism.

Core claim

When representative dsDNA parameters are used to estimate the geometrical spin current that exists for electrons forced to follow curved trajectories, the resulting current magnitude greatly exceeds the transport currents recorded in typical CISS measurements. Transport can therefore be interpreted as a weak leakage from these pre-existing curved spin-current states, and large CISS polarization emerges simply as the selective leakage of one spin branch rather than as a new spin polarization generated by the transport process itself.

What carries the argument

Geometrical spin current generated by electrons constrained to curved paths in a chiral molecular structure, whose magnitude is shown to be hierarchically larger than observed transport currents.

If this is right

  • Observed CISS polarization does not require microscopic spin-orbit interaction to be stronger than its known value in organic matter.
  • The measured transport current represents only a small fraction of the total spin current present in the chiral structure.
  • CISS appears as a selection effect among already-existing spin-current branches rather than a generation effect that creates net spin from an unpolarized source.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same leakage-selection picture could be tested in other chiral molecules whose geometry permits a comparable scale estimate.
  • Independent probes of the full geometrical spin current, rather than only the net transport current, would be needed to confirm the hierarchy.
  • Device designs that deliberately enhance the geometrical component while keeping transport leakage small might increase polarization without changing the molecular chemistry.

Load-bearing premise

The estimation of the intrinsic geometrical spin-current scale from representative dsDNA parameters really does produce values substantially larger than the transport currents measured in many CISS experiments.

What would settle it

An experiment that directly measures the total spin current circulating in a dsDNA junction and finds it comparable to or smaller than the net transport current would falsify the claimed hierarchy.

read the original abstract

Large spin polarization observed in chiral-induced spin selectivity (CISS) remains difficult to explain quantitatively. Experimental polarizations measured in chiral molecular systems are often substantially larger than expected from weak microscopic spin-orbit interaction in organic materials. We revisit the geometrical spin current introduced previously for electrons constrained to curved paths and propose a scale argument relevant to transport through double-stranded DNA (dsDNA). Estimation of the intrinsic geometrical spin-current scale using representative dsDNA parameters yields current magnitudes substantially larger than measured transport currents in many CISS experiments. We suggest that this hierarchy allows transport to be interpreted as weak leakage from underlying curved spin-current states. Within this picture, large CISS polarization emerges as transport selection of pre-existing spin-current branches.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 1 minor

Summary. The manuscript proposes that the large spin polarization observed in chiral-induced spin selectivity (CISS) experiments with double-stranded DNA arises from a hierarchy between transport currents and intrinsic geometrical spin currents associated with curved electron paths. Using representative dsDNA parameters, the authors estimate that the geometrical spin-current scale substantially exceeds typical measured transport currents, interpreting transport as weak leakage that selects pre-existing spin-current branches, thereby explaining the large polarization without invoking strong spin-orbit interactions.

Significance. If the scale hierarchy is robust, this work offers a novel perspective on CISS by linking it to geometrical constraints in chiral molecules, potentially resolving the discrepancy between weak microscopic SOI and observed large polarizations. It could stimulate further theoretical and experimental investigations into spin currents in curved geometries.

major comments (1)
  1. [Estimation of geometrical spin-current scale (main text)] The central claim depends on an order-of-magnitude estimation showing that the intrinsic geometrical spin-current magnitude exceeds measured transport currents. However, the manuscript does not supply the explicit numerical inputs (such as curvature radius, Fermi velocity, effective mass) or the intermediate derivation steps converting these to a current value. This absence makes it impossible to verify whether the claimed separation of scales holds or is sensitive to parameter variations, as noted in the abstract's description of 'representative dsDNA parameters'.
minor comments (1)
  1. The abstract and introduction could benefit from clearer definitions of 'geometrical spin current' and 'transport selection' to aid readers unfamiliar with the prior work referenced.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their constructive comment on the estimation details. We address it below and will revise the manuscript to include the requested numerical inputs and derivation steps.

read point-by-point responses

  1. Referee: [Estimation of geometrical spin-current scale (main text)] The central claim depends on an order-of-magnitude estimation showing that the intrinsic geometrical spin-current magnitude exceeds measured transport currents. However, the manuscript does not supply the explicit numerical inputs (such as curvature radius, Fermi velocity, effective mass) or the intermediate derivation steps converting these to a current value. This absence makes it impossible to verify whether the claimed separation of scales holds or is sensitive to parameter variations, as noted in the abstract's description of 'representative dsDNA parameters'.

    Authors: We agree the main text omitted explicit inputs and steps for the order-of-magnitude estimate. In revision we will add a short subsection (or appendix) listing the representative dsDNA parameters (helix radius 1 nm, Fermi velocity 10^5 m/s, effective mass 0.1 m_e) together with the intermediate steps from the geometrical spin-current expression to the ~nA scale, allowing direct verification of the hierarchy and sensitivity checks. This does not change the central claim but makes it reproducible. revision: yes

Circularity Check

0 steps flagged

No significant circularity; scale hierarchy is an external estimation, not a self-referential derivation.

full rationale

The paper's argument rests on estimating the geometrical spin-current magnitude (referenced from prior work) using representative dsDNA parameters and comparing it to independently measured transport currents from CISS experiments. This comparison supports an interpretive suggestion but does not reduce any claimed prediction or result to the inputs by construction. No equations are shown that equate a derived quantity to a fitted parameter or prior self-citation in a load-bearing loop. The estimation is presented as a scale argument rather than a fitted prediction, and external measurements provide the benchmark for the hierarchy. The derivation chain is therefore self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Only the abstract is available; no explicit free parameters, axioms, or invented entities are stated.

pith-pipeline@v0.9.1-grok · 5657 in / 1023 out tokens · 26032 ms · 2026-07-01T07:12:36.324772+00:00 · methodology

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Reference graph

Works this paper leans on

6 extracted references · 1 canonical work pages · 1 internal anchor

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    work page internal anchor Pith review Pith/arXiv arXiv 2026