Competition between magnetic relaxation mechanisms in exchange-coupled<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">Co</mml:mi><mml:mi mathvariant="normal">O</mml:mi><mml:mo>∕</mml:mo><mml:mi mathvariant="normal">Co</mml:mi></mml:mrow></mml:math>bilayers
Bibliographic record
Abstract
Transverse, ac-susceptibility measurements, $\ensuremath{\chi}(T)$, of polycrystalline [$\mathrm{Co}(8\phantom{\rule{0.3em}{0ex}}\mathrm{nm})∕\mathrm{Co}\mathrm{O}(x\phantom{\rule{0.3em}{0ex}}\mathrm{nm})$; $1\ensuremath{\leqslant}x\ensuremath{\leqslant}10$] bilayers are used to derive the magnetic anisotropy in an exchange-coupled ferromagnetic(FM)/antiferromagnetic(AFM) system. $\ensuremath{\chi}(T)$ was measured using the anisotropic magnetoresistance (AMR) induced by a small $(\ensuremath{\lesssim}5\phantom{\rule{0.3em}{0ex}}\mathrm{Oe})$ applied field at frequencies ranging from $40\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}400\phantom{\rule{0.3em}{0ex}}\mathrm{Hz}$. This low-field technique is sensitive to the full anisotropy field and to the distinctions between rotatable and nonrotatable anisotropy, reversible and dissipative contributions, and to the difference between the N\'eel and blocking temperatures, ${T}_{N}$ and ${T}_{B}$. The imaginary response shows three distinct mechanisms of relaxation, each with a different characteristic activation energy. These mechanisms are modelled succesfully using a simple magnetic free energy and thermal activation. Near ${T}_{B}$ the sample changes from a saturated FM state to an unpinned, multidomain FM state with no exchange bias. Near ${T}_{N}$, the sublattice magnetization of individual crystalline AFM grains switches between easy axes and the interfacial exchange anisotropy field disappears. At low temperature $(\ensuremath{\sim}70\phantom{\rule{0.3em}{0ex}}\mathrm{K})$, ferromagnetic exchange coupling of individual FM grains to the surrounding FM film can be bistable, creating soft FM degrees of freedom. This mechanism produces a rotatable anisotropy which dynamically inhibits these grains from contributing to the AFM interfacial exchange coupling. As these motions are frozen out at very low temperature, there is a large increase in the measured magnetic anisotropy which gives an important contribution to the difference in the exchange anisotropy as measured by low- and high-field techniques.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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; 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".