Magnetic domain observations on magnetite crystals in biotite and hornblende grains
Bibliographic record
Abstract
Magnetic domain structures have been observed on magnetite crystals in 300 μm to 1 mm size biotite and hornblende grains separated from drill core samples of Precambrian granodiorite basement in southern Alberta, Canada. The crystals were mounted in epoxy, and the surface was polished, first mechanically and then with a suspension of amorphous SiO2. Domain structures were observed on 6–60 μm magnetite crystals using the Bitter colloid technique. Observed features include lamellar domains bounded by straight 180° walls, closure domains, bent walls, wavy structures, and areas without visible domains. Crystals ≤50 μm in size generally have simple domain patterns with domain walls parallel to the long axis of the crystal. We studied domain wall displacements in small isolated magnetites as a function of applied magnetic field up to 24 mT. The number of domains decreases with increasing external field. Some walls are relatively mobile and disappear by 20 mT. Other walls remain immobile; in some cases, crystal defects or inclusions are seen to pin these walls, or segments of walls. An interesting observation was made on a 5 × 25 μm elongated magnetite crystal formed in a crack in hornblende. Large quantities of magnetic colloid gathered at either end of the crystal because of the strong flux leakage and pole fields at these locations. Colloid was also concentrated where domain boundaries intersect the sides of the crystal. With increasing applied field the colloid spread out to form patterns tracing complete external flux closure loops.
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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".