Bibliographic record
Abstract
Magnetic minerals acquire a remanent magnetization when cooled or warmed in an applied field H through a phase transition. This paper reports the first observations of transition cooling and warming remanent magnetizations (TrCRM and TrWRM) in pyrrhotite (Fe7S8) and hematite (αFe2O3), with phase transitions at 32 K (Besnus transition) and 250 K (Morin transition). TrWRM was produced by warming in a 2 mT field from 10 to 300 K and TrCRM by cooling in 2 mT from 300 to 10 K. In both experiments, magnetization M was measured at 5 K intervals. The largest changes in M occurred over a 20 K interval flanking the Besnus or Morin transition but substantial changes also occurred away from any transition, presumably due to continuous changes in anisotropy. The triclinic low-temperature phase of pyrrhotite has high remanence efficiency compared to the room-temperature monoclinic phase. When H was zeroed at 300 K, only 35–40% of M survived as TrWRM, but in TrCRM experiments when H was zeroed at 10 K, practically 100% of M was preserved. After zero-field cooling to 10 K, 50–60% of TrWRM was retained but <15% of TrCRM survived zero-field warming to 300 K. In hematite, both TrWRM of the room-temperature spin-canted phase and TrCRM of the low-temperature defect phase exist, as shown by net remanence production following complete warming–cooling or cooling–warming cycles between 10 and 300 K. Details of remanence acquisition/demagnetization in crossing the Morin transition could not be resolved, however. Symmetries were observed for both minerals. Single-domain size pyrrhotite crystals had mirror-image field-off and field-on warming curves below 32 K, during TrWRM production/TrCRM loss at the 32 K transition, and up to ≈150 K. Submicron single-domain hematite had almost complete symmetry between field-off and field-on curves during cooling as well as warming, both below and above the Morin transition but not in the transition region itself. This is the first time that mirror-image symmetries, observed previously for pseudo-single-domain and multidomain magnetite, have been documented for mineral grains in a single-domain state.
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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".