Thermoremanence and stable memory of single‐domain hematites
Bibliographic record
Abstract
We report thermoremanent magnetization (TRM) intensities and thermal demagnetization behavior of seven samples of single‐domain hematite (α Fe2O3) with grain sizes between 0.12 and 0.42 μm, before and after zero‐field cycling through the low‐temperature Morin transition (TM ≈ 240 K). TRM was unaffected by 100 mT alternating field demagnetization and by 600°C thermal demagnetization. Most demagnetization occurred between 625°C and the Néel temperature of 680–690°C. The TRM memory recovered after low‐temperature cycling was parallel to the original TRM and equally resistant to thermal demagnetization. TRM and TRM memory of single‐domain hematites are mainly due to the hard spin‐canted magnetism intrinsic to the crystal structure above the Morin transition, and not to the small and softer defect magnetism that survives below TM. However, the defect magnetism may play a role in renucleating the spin‐canted magnetism in a preferred direction during warming through TM. TRM intensities are well predicted by Neél single‐domain theory and increase in almost exact proportion to grain size. Although smaller than TRM intensities of multidomain hematites, single‐domain TRMs are potent sources of remanent magnetic anomalies, particularly for larger grains (10–15 μm), and are likely to be more stable over geological time than multidomain hematite TRMs.
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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".