Altermagnetism and superconductivity in a multiorbital <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>t</mml:mi> <mml:mo>−</mml:mo> <mml:mi>J</mml:mi> </mml:math> model
Bibliographic record
Abstract
Motivated by exploring correlated multiorbital altermagnets ($\text{A}\ensuremath{\ell}\text{Ms}$) we study minimal $t\ensuremath{-}J$ models on the square-octagon lattice, which favors such a collinear magnetic order. While antiferromagnetic order breaks translational and time-reversal symmetries, the $\text{A}\ensuremath{\ell}\text{M}$ state (equivalently, a ``$d$-wave ferromagnet'') features multipolar order, which separately breaks time-reversal and crystal rotation symmetries but preserves their product leading to spin-split bands with zero net magnetization. We study the mean-field phase diagram of these multiorbital models as we vary doping and interactions, discovering two types of $\text{A}\ensuremath{\ell}\text{M}$ order: (i) itinerant weak-coupling $\text{A}\ensuremath{\ell}\text{M}$ metals driven by quasi-1D van Hove singularities, as well as (ii) strong $\text{A}\ensuremath{\ell}\text{M}$ order at half-filling. We also find regimes of superconductivity including uniform $s$-wave and ${d}_{xy}$-wave pairing states, incipient ${d}_{xy}$-wave pair density wave order, and uniform phases with coexisting singlet-triplet pairing and $\text{A}\ensuremath{\ell}\text{M}$ order. Our inhomogeneous mean-field theory approach reveals that the coexistence phases are unstable to phase separation, but longer-range interactions could lead to stripe order. Our results may be relevant to studies of doping and pressure on $\text{A}\ensuremath{\ell}\text{M}$ materials.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.002 |
| Meta-epidemiology (broad) | 0.001 | 0.003 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.004 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.003 |
| Insufficient payload (model declined to judge) | 0.001 | 0.004 |
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".