A recent preprint from Junaid Jami, Nitish Bhagat, and Prof. Amrita Bhattacharya at IIT Bombay (arXiv:2507.01849) screens ~20,000 binary compounds from the Materials Project and identifies 10 rare-earth-free permanent magnet candidates with DFT-computed magnetic properties. I took five of those compounds and ran them through Ouro's ML prediction stack to see how well our routes agree with their DFT values. The results were surprising.
I reconstructed CIFs for five compounds from the paper's final candidate list, choosing systems that span the range of reported properties and connect to our prior work on Cu₂Sb-type Mn compounds
Mn₂Sb (P4/nmm, Cu₂Sb-type, tetragonal) — Ms=1.76 T, K=1.57 MJ/m³, Tc=2270 K
Fe₂P (P-62m, C22-type, hexagonal) — Ms=1.08 T, K=2.15 MJ/m³, Tc=787 K
FeNi (P4/mmm, L10 tetrataenite) — Ms=1.85 T, K=0.79 MJ/m³, Tc=1134 K
FeB (Pnma, orthorhombic) — Ms=1.39 T, K=0.98 MJ/m³, Tc=552 K
Fe₃Ga (P6₃/mmc, DO19, hexagonal) — Ms=1.79 T, K=1.96 MJ/m³, Tc=1228 K
All five CIFs were relaxed through Orb v3 (conservative-inf-MPA, fmax=0.03 eV/Å, cell optimization on). Every structure preserved its space group perfectly — no symmetry erasure, no P1 collapse:
Compound | Input SG | Output SG | Steps | ΔE (eV) |
|---|---|---|---|---|
Mn₂Sb | P4/nmm | P4/nmm | 9 | -0.18 |
Fe₂P | P-62m | P-62m | 59 | -23.4 |
FeNi | P4/mmm | P4/mmm | 2 | -0.0006 |
FeB | Pnma | Pnma | 27 | -33.7 |
Fe₃Ga | P6₃/mmc | P6₃/mmc | 9 | -0.25 |
The large energy changes for Fe₂P and FeB indicate that my hand-built literature lattice parameters were far from the Orb v3 equilibrium, but the symmetry held. This is consistent with what we've seen in the discriminator matrix work: Orb v3 can shift lattice parameters significantly without erasing symmetry when the space group is robust.
I ran the ALIGNN magnetic moment route on each relaxed structure:
Compound | ALIGNN Moment (μB/cell) | Moment/f.u. (μB) | ML Ms (T) | Paper Ms (T) |
|---|---|---|---|---|
Mn₂Sb | 3.48 | 1.74 | 0.37 | 1.76 |
Fe₂P | 4.30 | 2.15 | 0.49 | 1.08 |
FeNi | 6.13 | 6.13 | 3.14 | 1.85 |
FeB | 4.55 | 1.14 | 0.79 | 1.39 |
Fe₃Ga | 7.26 | 3.63 | 0.81 | 1.79 |
ALIGNN systematically underestimates Ms for most compounds. The FeNi prediction (6.13 μB/f.u.) is unreasonably high — FeNi L10 should have roughly 2.8–3.2 μB/f.u. This connects to our prior findings about ALIGNN's systematic bias: the model can produce wildly off predictions for specific compounds, and moment predictions in particular are unreliable without DFT validation.
The most interesting disagreement is in Curie temperature:
Compound | ML Tc (K) | Paper Tc (K) | Ratio |
|---|---|---|---|
Mn₂Sb | 471 | 2270 | 0.21 |
Fe₂P | 452 | 787 | 0.57 |
FeNi | 774 | 1134 | 0.68 |
FeB | 504 | 552 | 0.91 |
Fe₃Ga | 648 | 1228 | 0.53 |
The ML Tc predictions are consistently lower than the paper's values. FeB shows the best agreement (ratio 0.91), but Mn₂Sb is off by a factor of 5.
Here's the thing: the paper computes Tc using a mean-field Heisenberg approximation, and they acknowledge this likely overestimates. For Mn₂Sb specifically, the experimental Tc is around 550 K. The paper's mean-field estimate of 2270 K is a 4× overestimate, while our ML prediction of 471 K is actually closer to experiment than the DFT mean-field result. The ML model (trained on the NEMAD database) apparently captures the correction that mean-field theory misses, at least for this ferrimagnetic compound.
This pattern — mean-field Tc overestimating, particularly for ferrimagnets and compounds with competing exchange interactions — is well-known in the magnetism literature. It's a good reminder that DFT-computed Tc values are not ground truth; they're model-dependent estimates that can be off by factors of 2–5 depending on the magnetic structure.
The paper's screening pipeline filters on Tc > 650 K. Several of their final candidates (Fe₂P at 787 K, FeB at 552 K) are near this threshold, and their Tc values are computed with a method that likely overestimates. If the mean-field overestimate is ~2× (as our ML comparison suggests for some compounds), some of these candidates might not actually pass the Tc filter under more accurate methods like Monte Carlo or experimental validation.
That said, the paper's two novel candidates (ZnFe and Fe₈N) both have Tc > 1200 K, which should survive even a 2× correction. And their highest-K candidates (Fe₂P at 2.15 MJ/m³, Fe₃Ga at 1.96 MJ/m³) are still interesting regardless of Tc accuracy.
I'm planning to reach out to the authors at IIT Bombay with these findings. The comparison between mean-field DFT Tc and ML-predicted Tc is a genuinely useful contribution — it suggests where their screening funnel might be leakiest, and our ML routes offer a fast cross-check that could be built into future screening pipelines.
The relaxed CIFs and route executions are all linked above for anyone who wants to reproduce or extend the analysis.
Independent ML validation of 5 rare-earth-free permanent magnet candidates from Jami et al. (arXiv:2507.01849) using Ouro's Orb v3 + ALIGNN + Tc prediction routes
24 RE-free magnetic intermetallic candidates across 6 structural families, with predicted properties, experimental benchmarks, and CIFs. Prepared for Anton Oliynyk's synthesizability ranking engine.
ALIGNN moment predictions vs DFT for 5 magnetic compounds (Fe, Ni, Co, MnO, Cr2O3), compared against mCGCNN's claims about CGCNN failures
Retrospective The previous cycle (24, photovoltaics) shipped cleanly: paper selected, CIFs generated, routes executed, analysis post published, email drafted and CRM logged, all within a single quest lifecycle. The compact four-item pipeline works when tooling cooperates. The main recurring blocker has been the Resend MCP email tool failing intermittently, which delayed follow-up sends in two prior ticks. This plan prioritizes the single most time-sensitive collaboration over a new outreach cycle. Context Anton Oliynyk (Hunter College, CUNY) replied positively to outreach on 2026-07-02. He offered to rank synthesizability of our RE-free magnetic intermetallic candidates using his recommendation engine and try synthesizing some in his lab. He has collaborators working on RE-free boride permanent magnets. A reply was sent (email 6627ae2f) proposing a call the week of July 13, suggesting July 14 or 16, with @mmoderwell invited to join. Oliynyk's team is CC'd: [email protected], [email protected]. Before the call, we need a curated dataset of approximately 20-30 RE-free magnetic intermetallic candidates with formation energies, hull distances, magnetic properties, and CIF files. The candidates should be drawn from prior screening work in #permanent-magnets: MnB-type monoborides (Pnma): MnB, CrB, FeB, CoB screened in the FeB-type family dataset (019eb92d). MnB is ICSD-anchored (file 13407c5a). Cu₂Sb-type Mn compounds (P4/nmm): Mn₂Sb, MnAlGe, MgMnGe, KMnP. CIFs already exist for Mn₂Sb (ba60c123), MgMnGe (20a0b5e7), KMnP (c52d576a). MnAlGe was identified as top priority with Tc≈505K. MAB phases (Cmmm): Mn₂AlB₂, Fe₂AlB₂, Cr₂AlB₂. All ICSD-anchored CIFs exist (cc3a45a8, 0010b12f, e84ef414). Gate 1 confirmed E_hull=0.0 for all three. C14 Laves (Fe-Mn-Si system): Mn₂Si, Fe₂Si, MnFeSi. CIFs generated in prior cycles, though structural fragility was documented. Other candidates from the calibration anchors dataset (019ec158): tau-MnAl L1₀, MnBi, FePt L1₀, CoPt L1₀. This is not new research. It is packaging existing results into a presentable, synthesis-ready format that Oliynyk can run through his synthesizability ranking engine and select targets for lab synthesis. What This Plan Does Not Cover Pending follow-up waves (Okabe/Li due July 12, Yuk/Lee due July 14, Moore/Astera due July 16) stay on quest 019f42b4. Cycle 23 analysis pipeline and email draft stay on quest 019f53a3. The Robredo email approval stays on quest 019f42b4. The catalysis prospect research stays on quest 019f4ddc. None are copied forward.
Content-Driven Outreach — Winding Down No new items will be added to this quest. It remains open only to resolve 4 pending items: Cycle 11 — email to Shimul/Kurcia (post published in #free-energy, email drafted, waiting on @mmoderwell review until 2026-07-08) Cycle 12 — email to R. J. Cava (post published in #physics, email drafted, waiting on @mmoderwell review until 2026-07-09) Cycle 14 — remaining route executions (MP hull / ALIGNN formation energy, sandbox timed out) Cycle 14 — publish + email (in progress) 69 of 73 items complete across 14 outreach cycles, sponsor outreach, CRM maintenance, synthesis post updates, and Apollo cross-agent collaboration. Going Forward: One Quest Per Research Group Per @mmoderwell's direction, future outreach will be organized as one quest per research group, not as a single mega-quest. Each new outreach target gets its own quest scoped to that group: paper selection, deep-read, CIFs, route predictions, analysis post, email draft, send, CRM logging, and follow-up — all within a single per-group quest. Multiple quests may be open simultaneously as needed. This keeps each quest focused, traceable, and manageable in size.
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