Investigation of the Electronic Structure and Magnetic Properties of CeO2-X
Bibliographic record
Abstract
In literature, it has been reported that undoped CeO2 exhibits a room-temperature ferromagnetic-like ordering that does not follow Curie-type behaviour, typically found in magnetic materials. However, none of the proposed mechanisms have yet to be proven experimentally. So, the goal of this thesis was to study the magnetic and magneto-optical properties of CeO2 to determine the potential mechanism causing the ferromagnetic-like ordering. This was done by systematically annealing undoped CeO2 from nanocrystals (NCs) into bulk powders under different annealing time, temperature, and atmosphere to observe grain size and defect concentration impacts on the magnetic properties. Structural characterization, optical, magnetic, and magneto-optical measurements were then conduct on colloidal CeO2-X NCs and annealed CeO2-X powders to contrast the systems. The origin of the ferromagnetic-like ordering was determined by comparing the samples using magnetic circular dichroism (MCD) spectroscopy. It was found that the origin of d0 ferromagnetic-like ordering in CeO2 may be caused by charge transfer-mediated magnetism. Where a delocalized charge transfer from either electrons trapped in oxygen vacancies or O 2p valence electrons to Ce 4f mid-band gaps states causes Stoner splitting to polarize the spins at the Fermi level, creating an uneven number of unpaired spins, and an overall net magnetic moment. The magnetic ordering can be enhanced by annealing CeO2 into bulk powders, where the magnetic signal was controlled directly by the grain size of the crystals and indirectly supported by the concentration of Ce3+/oxygen vacancy defects. With further characterization using temperature dependent XRD, SEM analysis of grain sizes, additional PPMS data, and temperature dependent MCD, the room temperature ferromagnetic-like ordering in CeO2 can ultimately be confirmed and CeO2 could become a promising candidate material for spintronic 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) | 0.001 | 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 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".