Probing the Role of Dopant Oxidation State in the Magnetism of Diluted Magnetic Oxides Using Fe-Doped In<sub>2</sub>O<sub>3</sub> and SnO<sub>2</sub> Nanocrystals
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Bibliographic record
Abstract
Investigation of the origin of high-Curie temperature ferromagnetism in diluted magnetic oxides has become one of the focal points of research on solid-state magnetism. While several possible mechanisms have been proposed theoretically, broader experimental evidence is still lacking. Here we report a comparative study of the electronic structure and magnetic properties of colloidal Fe-doped In 2 O 3 and SnO 2 nanocrystals, as building blocks for grain-boundary-rich diluted magnetic oxide films. The dopant ions in both nanocrystal host lattices are principally in 3+ oxidation state, with possibly a minor presence of Fe 2+ in In 2 O 3, and no conclusive evidence of the presence of Fe 2+ in SnO 2 nanocrystals. Subsequently, we found that Fe-doped In 2 O 3 nanocrystalline films exhibit only minor ferromagnetic ordering (with a magnetic moment of less than ca. 0.1 μ B /Fe) and decreasing saturation magnetization with increasing doping concentration at room temperature. The saturation magnetic moment of Fe-doped SnO 2 nanocrystalline films is insignificant or below the detection limit. These results contrast previous findings for analogous Mn-doped nanocrystals, which contain mixed oxidation states (Mn 2+ and Mn 3+ ) and exhibit a robust ferromagnetism at room temperature. The correlation between the mixed dopant oxidation states and the observed magnetic properties implies that ferromagnetism in these systems is of a Stoner type, enabled by electron transfer between dopant ions and the local defect states arising from the grain boundaries within a nanocrystalline film. These results suggest the prospect of probing and manipulating ferromagnetism in nonmagnetic oxides by simultaneous control of the transition metal dopant oxidation states and extended structural defects.
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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 | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 it