Structural, electronic, and magnetic properties of nearly ideal <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>J</mml:mi><mml:mrow><mml:mi>e</mml:mi><mml:mi>f</mml:mi><mml:mi>f</mml:mi></mml:mrow></mml:msub><mml:mo>=</mml:mo><mml:mfrac><mml:mn>1</mml:mn><mml:mn>2</mml:mn></mml:mfrac></mml:mrow></mml:math> iridium halides
Bibliographic record
Abstract
Heavy transition metal magnets with ${J}_{eff}=\frac{1}{2}$ electronic ground states have attracted recent interest due to their penchant for hosting new classes of quantum spin liquids and superconductors. Unfortunately, model systems with ideal ${J}_{eff}=\frac{1}{2}$ states are scarce due to the importance of noncubic local distortions in most candidate materials. In this work, we identify a family of iridium halide systems [i.e., ${\mathrm{K}}_{2}\mathrm{Ir}{\mathrm{Cl}}_{6}$, ${\mathrm{K}}_{2}\mathrm{Ir}{\mathrm{Br}}_{6}$, ${({\mathrm{NH}}_{4})}_{2}\mathrm{Ir}{\mathrm{Cl}}_{6}$, and ${\mathrm{Na}}_{2}\mathrm{Ir}{\mathrm{Cl}}_{6}\ifmmode\cdot\else\textperiodcentered\fi{}6({\mathrm{H}}_{2}\mathrm{O})]$ with ${\mathrm{Ir}}^{4+}$ electronic ground states exhibiting extremely small deviations from the ideal ${J}_{eff}=\frac{1}{2}$ limit. We also find ordered magnetic ground states for the three anhydrous systems, with single-crystal neutron diffraction on ${\mathrm{K}}_{2}\mathrm{Ir}{\mathrm{Br}}_{6}$ revealing type-I antiferromagnetism. This spin configuration is consistent with expectations for significant Kitaev exchange in a face-centered-cubic magnet. This work establishes that incorporating isolated $\mathrm{Ir}{X}_{6}$ octahedra in materials, where $X$ is a halogen ion with a low electronegativity, is an effective design principle for realizing unprecedented proximity to the pure ${J}_{eff}=\frac{1}{2}$ state. At the same time, we highlight undeniable deviations from this ideal state, even in clean materials with ideal $\mathrm{Ir}{X}_{6}$ octahedra as inferred from the global cubic crystal structures.
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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) | 0.003 | 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".