Single-crystalline HfO2 nanostructures with novel ferromagnetic properties
Bibliographic record
Abstract
Hafnium oxide (HfO 2 ) has special technological significance due to its superior properties such as high dielectric constant (κ∼25), wide bandgap (∼5.7 eV), and superb thermal and chemical stabilities. Its room-temperature ferromagnetism and excellent CMOS technology compatibility make it a promising candidate for seamless CMOS-spintronics integration. Low-dimensional single-crystalline HfO 2 nanostructures, particularly one dimensional (1D) nanostructures, are expected to exhibit enhanced ferromagnetic properties due to large specific surface areas and potentially more surface defects. To date, the synthesis of single-crystalline HfO 2 1D nanostructures has, however, remained elusive. Here, single-crystalline dopant-free HfO 2 nanostructures with notable morphologies, including HfO 2 1D nanostructures, are grown using catalyst-assisted pulsed laser deposition. It is shown that Sn plays a crucial role in producing these 1D nanostructures by increasing both the VLS nucleation and growth rates. Magnetization measurements reveal room-temperature ferromagnetism in HfO 2 nanowires, contrasting with weak paramagnetic responses in HfO 2 nanostructured films. We also provide the first direct evidence of oxygen vacancies as the source of room-temperature ferromagnetism in HfO 2 . To account for the observed magnetic property, we employ a modified bound magnetic polaron-band ferromagnetism hybrid model, which is also generally applicable to dopant-free nanostructures of other metal oxides. This work provides new insights into the growth of novel metal oxide 1D nanostructures and the design of new dilute magnetic semiconducting oxides for potential integrated CMOS-spintronics applications. • This study marks the first successful fabrication of single-crystalline 1D HfO 2 nanostructures. • Sn-Gold Nano Island alloy-catalysts play a crucial role in producing 1D HfO 2 nanostructures. • HfO 2 NWs exhibit novel room-temperature ferromagnetism in contrast to HfO 2 nanostructured films. • Direct evidence for the oxygen-vacancy-induced ferromagnetism in HfO 2 is provided by X-ray photoelectron spectroscopy. • These HfO 2 1D nanostructures hold great promise for integrated CMOS-spintronics applications.
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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) | 0.000 | 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 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".