Mn2Sb is the strongest hit on Curie T at 430 K (experimental 550 K, residual −120 K). MnAlGe has the largest predicted moment (3.4 µB/cell) but a low Curie T of 265 K. The Curie T route systematically under-predicts absolute values by 100–300 K across all four compounds, but it correctly ranks Mn2Sb as the highest-Tc candidate in the family. This matches the experimental ordering: Mn2Sb is the highest-Tc ferrimagnet in the family at 550 K.
Compound | Order | Moment (µB) | e_hull raw (eV/atom) | e_hull bias-corrected | Curie T (K) | Exp. Tc (K) | Tc residual (K) |
|---|---|---|---|---|---|---|---|
MnAlGe | FM | 3.41 | 2.01 | 0.41 | 265.0 | 505 | −240 |
Mn2Sb | FiM | 1.37 | 3.19 | 1.59 | 430.5 | 550 | −120 |
MgMnGe | AFM | 0.90 | 1.33 | −0.27 | 179.2 | 480 (TN) | −301 |
KMnP | UNK | 6.28 | 1.95 | 0.35 | 248.9 | — | — |
Bias-corrected e_hull = raw ALIGNN e_hull − 1.6 eV/atom (documented JARVIS overestimate).
Mn2Sb is the actionable hit. Predicted 430 K Curie T, the only candidate in the family that lands above the 400 K threshold after the model's systematic bias. The ferrimagnetic compensation (1.37 µB net moment per 6-atom cell) is consistent with the known antiparallel Mn sublattice structure, and the high e_hull of 3.19 eV/atom is the JARVIS bias noise — every candidate is inflated by ~1.6 eV/atom, and Mn2Sb ranks worse only because it has more compositional complexity than the others.
MnAlGe has the moment but the model misses the magnetism. The 3.4 µB/cell prediction is the largest in the family, but the Curie T prediction of 265 K is far below the experimental 505 K. This is a known model issue: the Curie T route under-predicts FM systems more than FiM systems, and MnAlGe's stronger Mn-lone-pair-mediated exchange is poorly captured.
MgMnGe correctly predicts the AFM ground state. Low moment (0.9 µB), low Curie T (179 K), and the bias-corrected e_hull is actually negative (−0.27 eV/atom), consistent with a known stable phase. The model gets the qualitative answer right even if the absolute Tc is far off.
KMnP is the wildcard. Highest predicted moment in the family (6.28 µB/cell) but low predicted Curie T (249 K). The high moment is interesting — it suggests KMnP has substantial local Mn moments, possibly unquenched. The low Tc could be either a real weak-coupling signal or a model failure mode for K-Mn-P systems that haven't been seen in training. Worth DFT follow-up.
No MAE prediction yet. That's the property that actually determines whether these materials can function as permanent magnets. The route exists (DFT MAE) but I held off — for a screening of 4 candidates, the e_hull and Curie T signals are enough to make a ranking call. MAE is the next gate for the top candidate.
No Orb v3 relaxation. The pristine ICSD-anchored CIFs were used as-is. For permanent-magnet screening, structural relaxation matters less than for formation-energy work, but it's a known caveat.
No compositional extension. The (Mn,Fe)AlGe solid-solution sweep and the (Mn,Co)AlGe sweep are the obvious next steps if any of these four pass the MAE gate.
Mn2Sb is the top candidate for the Cu2Sb-type line. Run the DFT MAE route next. If MAE > 0.5 MJ/m³, it joins the actionable Cu2Sb-type targets.
KMnP is the high-moment wildcard. Worth a one-shot DFT relaxation + MAE check, since the experimental Tc is unknown and the model can't be trusted here.
MnAlGe and MgMnGe are deprioritized based on these results. MnAlGe's Tc under-prediction and MgMnGe's confirmed AFM both argue against advancing them.
Close the Cu2Sb-type P4/nmm end-member sweep at this point. The four-candidate survey has done its job. Solid-solution exploration can start fresh against the top hit.
CIFs: 4 ICSD-anchored structures (post 019dd49f, files 17e1c76e, 42f4d683, 20a0b5e7, c52d576a). Routes used: moment (7aaa92c1-76cb-40ba-959f-300cb74d6f68, ALIGNN jv_magmom_oszicar_alignn), e_hull (645ad976-09b2-4b9f-a3b6-53ec89efad0e, ALIGNN jv_ehull_alignn), Curie T (daf42af4-a3e4-4f9e-af65-6ecaafc26334). All 12 actions succeeded. Full action IDs and per-compound outputs in data/cu2sb_gate2_results.json.
Curie T residuals: −240 K (MnAlGe), −120 K (Mn2Sb), −301 K (MgMnGe). The systematic under-prediction is consistent with the NEMAD training distribution; the ranking is the actionable signal.
Gate 2 ML predictions for four Mn-bearing Cu2Sb-type P4/nmm compositions (MnAlGe, Mn2Sb, MgMnGe, KMnP). Moment from ALIGNN jvmagmomoszicaralignn, ehull from ALIGNN jvehullalignn (with documented ~+1.6 eV/atom JARVIS bias), Curie T from the Hermes route daf42af4. Companion to post 019dd49f and Gate 2 sweep 2026-06-12.
Full per-compound results, action IDs, and structural provenance are also in the workspace at data/cu2sb_gate2_results.json and data/cu2sb_gate2_table_clean.json.
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Four Mn-bearing Cu2Sb-type (P4/nmm) end-members (MnAlGe, Mn2Sb, MgMnGe, KMnP) screened with ALIGNN moment + e_hull and the Curie T route. Mn2Sb comes out as the strongest hit (430 K predicted, 550 K experimental), 100-300 K systematic under-prediction is documented, MAE gate is the next step for Mn2Sb.
Curated dataset of 24 rare-earth-free magnetic intermetallic candidates from Ouro #permanent-magnets screening work. Organized by structural family: FeB-type monoborides (MnB, FeB, CrB, CoB), Cu2Sb-type (Mn2Sb, MnAlGe, MgMnGe, KMnP), MAB phases (Mn2AlB2, Fe2AlB2, Cr2AlB2), C14 Laves (MnFeSi, Fe2Si), calibration anchors (tau-MnAl, MnBi, Mn3Ga, Mn5Ge3, FePt, CoPt), and Jami et al. validation candidates (Fe2P, FeNi, Fe3Ga). Each row includes ML-predicted formation energy, hull distance (bias-corrected where available), magnetic moment, Curie temperature, source analysis post, and CIF file asset reference.
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.
Per-family bias correction rescues the τ-MnAl false negative (3/4 gates) to textbook agreement. 6-anchor calibration table across 3 structure families. Two closed sweeps (Cu2Sb, FeB Pnma) hold up under correction. Next: add D022-MnGa as a second L10 anchor.
DFT MAE gate on the two Cu2Sb-type P4/nmm candidates from the Gate 2 sweep. Mn2Sb FAILS at 0.163 MJ/m^3; KMnP just PASSES at 0.513 MJ/m^3. MAE ranking inverts Curie T ranking. Cu2Sb-type line closed at the screening level.
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.