Enhanced orbital anisotropy through the proximity to a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>SrTi</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math> layer in the perovskite iridate superlattices
Bibliographic record
Abstract
We have used angle-dependent soft x-ray absorption spectroscopy (XAS) at the O $K$ edge and first-principles calculations to investigate the electronic structures of iridate-based superlattices ${(\mathrm{SrIr}{\mathrm{O}}_{3})}_{m}/(\mathrm{SrTi}{\mathrm{O}}_{3})$ ($m=1$, 2, 3, and \ensuremath{\infty}). We focus on the pre-edge Ir $5d {t}_{2g}--\mathrm{O} 2p$ orbital hybridization feature in the XAS spectra. By varying the measurement geometry relative to the incident photon polarization, we are able to extract the dichroic contrast and observe the systematic increase in the anisotropy of Ir $5d$ orbitals as $m$ decreases. First-principles calculations elucidate the orbital anisotropy coming mainly from the enhanced out-of-plane compression of $\mathrm{Ir}{\mathrm{O}}_{6}$ octahedra in the $\mathrm{SrIr}{\mathrm{O}}_{3}$ layers that are adjacent to the inserted $\mathrm{SrTi}{\mathrm{O}}_{3}$ layers. As $m$ decreases, the increased volume fraction of these interfacial $\mathrm{SrIr}{\mathrm{O}}_{3}$ layers and their contact with the $\mathrm{SrTi}{\mathrm{O}}_{3}$ layers within the ${(\mathrm{SrIr}{\mathrm{O}}_{3})}_{m}/(\mathrm{SrTi}{\mathrm{O}}_{3})$ supercell lead to enhanced orbital anisotropy. Furthermore, the tilt and rotation of $\mathrm{Ir}{\mathrm{O}}_{6}$ octahedra are shown to be essential to understand the subtle orbital anisotropy in these superlattices, and constraining these degrees of freedom will give an incorrect trend. Our results demonstrate that the structural constraint from the inserted $\mathrm{SrTi}{\mathrm{O}}_{3}$ layers, in addition to other electronic means such as polar interface and charge transfer, can serve as a knob to control the orbital degree of freedom in these iridate-based superlattices.
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How this classification was reachedexpand
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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.003 |
| Bibliometrics | 0.000 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.003 | 0.002 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.044 | 0.005 |
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; both teacher heads agree on what is shown here.
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".