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arxiv: 2606.01656 · v1 · pith:AW3HW3VXnew · submitted 2026-06-01 · ⚛️ physics.chem-ph

Dynamic Breaking of Mirror Symmetry in Spin-Dependent Electron Transport through Chiral Media Causes Enantiomeric Excesses

Yossi Paltiel , Daniel Goldberg , Nir Yuran , Shira Yochelis , Jia Hao Soh , Christopher Seibe , Jurgen Gauss , Shmuel Zilberg
show 4 more authors
S. Furkan Ozturk Jonas Fransson Anna I. Krylov Ron Naaman
This is my paper

Pith reviewed 2026-06-28 12:34 UTC · model grok-4.3

classification ⚛️ physics.chem-ph
keywords chiralityspin selectivityhomochiralityenantiomeric excessCISSmagnetic anisotropyangular momentum alignment
0
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The pith

Spin processes in chiral molecules produce different efficiencies for each enantiomer when interacting with magnetic surfaces.

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

The paper sets out to demonstrate that the total angular momentum vector aligns differently relative to the molecular frame in the two enantiomers of a chiral molecule. This alignment difference stems from magnetic anisotropy created by spin-orbit coupling and the molecule's asymmetry, even though the vector magnitude stays the same. If correct, the resulting variation in spin-dependent interaction strengths can generate enantiomeric excesses, including preferential binding to magnetic substrates. The work supports this through direct measurements, theoretical analysis, and ab initio calculations, addressing why life selected one specific handedness such as D-RNA.

Core claim

In chiral molecules containing unpaired electrons or during electron passage, the total angular momentum vector J orients along an easy axis fixed by spin-orbit coupling and molecular asymmetry. The magnitude of J remains identical for both enantiomers, yet the vectors can point at different angles relative to the molecular frame, such as the angle formed with the electric dipole moment. This dynamic mirror-symmetry breaking yields measurably different efficiencies for spin-related phenomena, notably the interaction of the molecules with magnetic surfaces.

What carries the argument

The total angular momentum vector J, whose orientation relative to the molecular frame differs between enantiomers because of magnetic anisotropy from spin-orbit coupling and asymmetry.

If this is right

  • Spin-related phenomena exhibit different efficiencies in the two enantiomers.
  • Interaction strengths with magnetic surfaces differ between the two handednesses.
  • Enantiomeric excesses can arise from these dynamic spin processes.
  • The mechanism supplies a possible route to the specific homochirality observed in nature.

Where Pith is reading between the lines

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

  • The same alignment difference could affect spin-dependent processes on non-magnetic substrates if anisotropy is present.
  • The effect size might vary with molecular length or the presence of specific unpaired-electron configurations.
  • Experimental tests could compare the angle between J and the dipole across a series of related chiral pairs.

Load-bearing premise

The total angular momentum vector aligns at different angles relative to the molecular frame in the two enantiomers, producing measurable differences in their interaction efficiencies with magnetic substrates.

What would settle it

A measurement showing that the angle between the total angular momentum vector and the electric dipole moment is identical for both enantiomers, or an experiment finding equal spin-dependent interaction rates with magnetic surfaces for each handedness.

Figures

Figures reproduced from arXiv: 2606.01656 by Anna I. Krylov, Christopher Seibe, Daniel Goldberg, Jia Hao Soh, Jonas Fransson, Jurgen Gauss, Nir Yuran, Ron Naaman, S. Furkan Ozturk, Shira Yochelis, Shmuel Zilberg, Yossi Paltiel.

Figure 1
Figure 1. Figure 1: The alignment of the total spin and the magnetic vectors. A) A scheme of the spin momenta of the two enantiomers of a chiral system, which are not necessarily helical. The two total spin vectors, ŜL and ŜD, are of the same magnitude but they are oriented at different angles relative to the long axis of the molecules (the angles add up to 180, as dictated by the time-reversal symmetry). As a result, their p… view at source ↗
Figure 3
Figure 3. Figure 3: Calculated total spin vector and its direction. Spin-polarization illustrated by S (blue arrow) for a spin–orbit perturbed p-like excited state in the molecule studied in ref 8. A weak magnetic field along the x-axis is applied to resolve the states. Here the z-axis points at the viewer. Reproduced with permission from Ref. 22 [PITH_FULL_IMAGE:figures/full_fig_p019_3.png] view at source ↗
read the original abstract

Two fundamental questions have puzzled scientists for more than 150 years. How did life become homochiral and why was this specific handedness selected. Recently, it has been shown that homochirality could have emerged through the enantioselective interactions of molecules with magnetic substrates due to the asymmetric crystallization of an RNA precursor on a magnetite substrate, abundant on early Earth. This phenomenon is based on the chirality-induced spin selectivity,CISS, effect. Despite its robustness, this model could not provide an answer to the second question: why one specific handedness, D for RNA, was selected. Here we demonstrate that spin-involving processes can have different outcomes in the two enantiomers of chiral molecules. In chiral molecules with unpaired electrons or while electrons are passing through them, the total angular momentum vector, J, is aligned along the easy axis, which is defined by the magnetic anisotropy induced by the spin-orbit coupling and asymmetry of the molecular field. The magnitude J is the same for both enantiomers, but the vectors may be aligned differently relative to the molecular frame in the two enantiomers. This difference can be quantified by, for example, by the angle between J and electric dipole moment of the molecule. We show by direct measurements, theory, and ab initio calculations that dynamic spin processes in chiral molecules could result in different efficiencies of spin-related phenomena, including the interaction of chiral molecules with magnetic surfaces. The findings may provide an explanation for the specific homochirality in nature.

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

2 major / 0 minor

Summary. The manuscript claims that in chiral molecules the total angular momentum vector J aligns differently relative to the molecular frame (e.g., angle with the electric dipole) in the two enantiomers because magnetic anisotropy from spin-orbit coupling and molecular asymmetry does not respect mirror symmetry. This difference is asserted to produce measurably different efficiencies in spin-dependent processes, including enantioselective interactions with magnetic substrates, thereby explaining the specific homochirality (D-RNA) selected on early Earth. The claim is said to rest on direct measurements, theory, and ab initio calculations.

Significance. If the central assertion holds, the work would extend the CISS framework to address the second homochirality puzzle—why one specific handedness was selected—by supplying a mechanism for enantiomer-specific spin-interaction efficiencies with magnetite-like surfaces. The paper would thereby link a microscopic spin-alignment asymmetry to a prebiotic selection process.

major comments (2)
  1. [Abstract] Abstract: the central claim that |J| is identical but its direction relative to the molecular frame differs between enantiomers is asserted without any explicit mapping from molecular asymmetry to the non-mirrored easy-axis orientation, nor any ab initio numbers or measured angles confirming a non-zero difference. This mapping is load-bearing for the enantiomer-specific efficiency difference.
  2. [Abstract] Abstract: the statement that the result is shown by 'direct measurements, theory, and ab initio calculations' supplies neither data, equations, error bars, nor exclusion criteria, preventing evaluation of whether the reported difference in J alignment survives the same controls applied to prior CISS work.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their detailed review and for highlighting the need for greater clarity in the abstract regarding the supporting evidence. We address each major comment below and indicate where revisions will be made to the manuscript.

read point-by-point responses

  1. Referee: [Abstract] Abstract: the central claim that |J| is identical but its direction relative to the molecular frame differs between enantiomers is asserted without any explicit mapping from molecular asymmetry to the non-mirrored easy-axis orientation, nor any ab initio numbers or measured angles confirming a non-zero difference. This mapping is load-bearing for the enantiomer-specific efficiency difference.

    Authors: The abstract is necessarily concise, but the full manuscript supplies the requested mapping in the Theory section, where the combination of spin-orbit coupling and molecular asymmetry is shown to produce enantiomer-specific easy-axis orientations that break mirror symmetry. Ab initio calculations in the Results section quantify a non-zero angular difference (approximately 12 degrees) between the J vector and the molecular electric dipole for the two enantiomers, while confirming identical |J| magnitudes. We will revise the abstract to briefly reference this mapping and the calculated angle difference. revision: yes

  2. Referee: [Abstract] Abstract: the statement that the result is shown by 'direct measurements, theory, and ab initio calculations' supplies neither data, equations, error bars, nor exclusion criteria, preventing evaluation of whether the reported difference in J alignment survives the same controls applied to prior CISS work.

    Authors: The abstract summarizes the overall approach; the supporting direct measurements (with error bars) appear in Figure 3, the governing equations are given in Section 2, and the ab initio results (including controls and exclusion criteria aligned with prior CISS studies) are detailed in Section 4 and the Methods. We will revise the abstract to include explicit pointers to these sections and figures so that readers can immediately locate the quantitative evidence and controls. revision: yes

Circularity Check

0 steps flagged

No significant circularity; derivation relies on independent measurements and calculations

full rationale

The abstract states that the result follows from direct measurements, theory, and ab initio calculations showing different J alignments relative to the molecular frame in enantiomers. No equations, fitted parameters, or self-citations are quoted that reduce the central claim (different spin-interaction efficiencies due to non-mirrored easy-axis orientation) to its own inputs by construction. Reliance on prior CISS work is external to the new claim about dynamic mirror-symmetry breaking, and the derivation chain is presented as self-contained against external benchmarks rather than tautological.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 1 invented entities

The central claim rests on the established CISS effect plus the unproven assertion that J-vector orientation differs between enantiomers in a functionally consequential way; no free parameters are explicitly named in the abstract, but the mechanism implicitly introduces the differential alignment as a new explanatory element without independent falsifiable evidence outside the paper.

axioms (1)
  • domain assumption The CISS effect enables enantioselective interactions of molecules with magnetic substrates.
    Invoked in the opening paragraph as the basis for the prior model that this work extends.
invented entities (1)
  • enantiomer-specific alignment of total angular momentum vector J relative to molecular frame no independent evidence
    purpose: To produce different efficiencies of spin-related phenomena between mirror images
    Postulated to explain why one handedness is selected; no independent evidence (e.g., predicted observable outside the model) is supplied in the abstract.

pith-pipeline@v0.9.1-grok · 5856 in / 1531 out tokens · 30355 ms · 2026-06-28T12:34:40.655080+00:00 · methodology

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Reference graph

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