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 distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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) | 0.003 | 0.001 |
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; both teacher heads agree on what is shown here.
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".