Substituent effects on exchange anisotropy in single- and multiorbital organic radical magnets
Bibliographic record
Abstract
The contribution of heavy-atom substituents to the overall spin-orbit interaction in two classes of organic radical molecular magnets is discussed. In ``single-orbital'' radicals, spin-orbit coupling (SOC) effects are well described with reference to pairwise anisotropic exchange interactions between singly occupied spin-bearing orbitals on neighboring molecules; anisotropy requires the presence of spin density on heavy-atom sites with principal quantum number $n>3$. In ``multiorbital'' radicals, SOC involving virtual orbitals also contributes to anisotropic exchange and, as a result, the presence of heavy ($n>3$) atoms in formally non-spin-bearing sites can enhance pseudodipolar ferromagnetic interaction terms. To demonstrate these effects, ferromagnetic and antiferromagnetic resonance spectroscopies have been used to probe the exchange anisotropy in two organic magnets, one a ``single-orbital'' ferromagnet, the other a ``multiorbital'' spin-canted antiferromagnet, both of which contain a heavy-atom iodine ($n=5$) substituent. While the symmetry of the singly occupied molecular orbital in both radicals precludes spin-orbit contributions from iodine to the overall exchange anisotropy, the symmetry and energetically low-lying nature of the lowest unoccupied molecular orbital in the latter allows for appreciable spin density at the site of iodine substitution and, hence, a large exchange anisotropy.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".