Magnetization reversal dynamics in epitaxial spin-valve structures
Bibliographic record
Abstract
We report the dynamic hysteresis behavior of epitaxial single ferromagnetic NiFe, Co layers, and NiFe/Cu/Co spin-valve structures investigated as a function of field sweep rate $\mathrm{H\ifmmode \dot{}\else \.{}\fi{}}(dH/dt)$ in the range 0.01--270 kOe/sec using the magneto-optic Kerr effect. In situ reflection high-energy electron-diffraction images confirmed that the NiFe, Cu, and Co layers grew epitaxially in the (100) orientation where the fcc NiFe, Co〈110〉 in-plane directions correspond to the Si〈100〉 directions. For $\mathrm{Cu}/60\AA{}\mathbf{NiFe}/\mathrm{C}\mathrm{u}/\mathrm{S}\mathrm{i}{(H}_{c}=5\mathrm{Oe})$ and $\mathrm{Cu}/40\AA{}\mathbf{Co}/\mathrm{C}\mathrm{u}/\mathrm{S}\mathrm{i}{(H}_{c}=104\mathrm{Oe})$ single magnetic layer structures, the hysteresis loop area A is found to follow the scaling relation $A\ensuremath{\propto}{H}^{\ensuremath{\alpha}}$ with $\ensuremath{\alpha}\ensuremath{\sim}0.13$ and \ensuremath{\sim}0.02 at low sweep rates and \ensuremath{\sim}0.70 and \ensuremath{\sim}0.30 at high sweep rates, respectively. This result indicates that the NiFe and Co layers in the spin-valve structures can be expected to show distinct scaling behavior at high sweep rate. We found that the ``double-switching'' behavior which occurs at low sweep rates transforms to ``single switching'' at \ensuremath{\sim}154 kOe/sec and \ensuremath{\sim}192 kOe/sec, respectively, for the single and double spin valves due to the different dynamic response of the NiFe and Co layers. Our results provide direct experimental evidence that the magnetic anisotropy strength affects dynamic hysteresis scaling in ultrathin magnetic films, in contrast with the predictions of current theoretical models.
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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) | 0.000 | 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) | 0.036 | 0.002 |
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".