Shear‐Mediated Stabilization of Spin Spiral Order in Multiferroic NiI <sub>2</sub>
Bibliographic record
Abstract
Abstract Type‐II multiferroicity from non‐collinear spin order is recently explored in the van der Waals material NiI 2 . Despite the importance for improper ferroelectricity, the microscopic mechanism of the helimagnetic order remains poorly understood. Here, the magneto‐structural phases of NiI 2 are investigated using resonant magnetic X‐ray scattering (RXS) and X‐ray diffraction. Two competing magnetic phases are identified. Below 60 K, an incommensurate magnetic reflection ( q ≈ [0.143,0,1.49] reciprocal lattice units) is observed which exhibits finite circular dichroism in RXS, signaling the inversion symmetry‐breaking helimagnetic ground state. At elevated temperature, in the non‐polar phase (60 K < T < 75 K), a distinct q ≈ [0.087,0.087,1.5] magnetic order is observed, attributed to a collinear incommensurate (CI) state. The first‐order CI‐helix transition is concomitant with a structural transition characterized by a significant interlayer shear, which drives the helimagnetic ground state as evidenced by a mean‐field Heisenberg model including interlayer exchange and its coupling to the structural distortion. These findings identify interlayer magneto‐structural coupling as the key driver behind multiferroicity in NiI 2 .
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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 teacher head, 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".