Magnetic ordering in double perovskites with 4d and 5d elements
Bibliographic record
Abstract
B-site ordered double perovskites of the type AA′BB′O6 have attracted attention recently due to unusual and unpredictable modes of magnetic order. Of particular interest are materials where AA′ = Ba, Sr or La and B′ = Mo,Ru,Os and Re and B is a diamagnetic ion such as Li+,Na+,Ca2+, Mg2+, Zn2+ or Cd2+.Crystal symmetries encountered are Fm-3m, I4/m and P21/n as a function of the Goldschmidt tolerance factor which in turn impose local symmetries at the magnetic B′ site of m-3m, 4/m and -1, respectively. The magnetic ions have electronic configurations 4d1, 4d3,5d1, 5d2 and 5d3 with nominal spins, S = 1/2,1 and 3/2. Spin orbit coupling is very large, reaching ~ 0.5eV for the 5d ions, and plays a more important role than in the more familiar 3d-based magnetic materials. Geometric frustration, the B′ ion sublattice is f.c.c., based on edge sharing tetrahedra, also is of critical importance. Observed magnetic ground states range from spin glasses (without apparent disorder), collective spin singlets, ferromagnets and antiferromagnets. Often, ordered moments are a small fraction of a Bohr magneton. Systematic behavior is elusive. For example Ba2YReO6 and Ba2CaOsO6 (both Fm-3m) have the same unit cell constant to within .01 % and both are based on 5d2 ions but the former is a highly unconventional spin glass and the latter orders antiferromagnetically below 50K. Recent results on this class of magnetic materials will be described in the context of existing theories.
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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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".