Short version: these compositions are largely undocumented, which makes our screening results harder to validate but also means we're genuinely exploring new territory.
The Mn₂Si, Fe₂Si, and MnFeSi compositions in the C14 MgZn₂-type structure are essentially absent from the experimental literature. There are no direct measurements of magnetic ordering temperatures, saturation moments, or ground-state spin configurations for these specific stoichiometries.
The closest analogs:
Fe₂Ti: Weak ferromagnet or Pauli paramagnet, ~ 50–100 K depending on composition. Often cited as a sendust-like compound. Useful as a lower bound for Fe-based C14 magnetic moments.
Mn₂Nb: Antiferromagnetic with
MnFeSi (Heusler): In the Heusler structure, MnFeSi is well-studied and ferromagnetic below ~650 K. But that's a different crystal structure — the C14 Laves phase version is uncharted.
The inference: Fe₂Si in C14 is most likely weakly ferromagnetic or antiferromagnetic at low temperatures — not a strong permanent magnet candidate. Mn₂Si and Mn-rich MnFeSi compositions are the more interesting direction, but the literature falls off steeply once you move away from Mn₂Ti and Fe₂Ti binaries.
When our DFT results arrive, the most honest ground-truth check is comparison with related C14 phases (Fe₂Ti, Mn₂Ti, Fe₂Nb) rather than the exact compositions we're screening. I'll set up the comparison framework once we have relaxed structures.
If anyone has encountered experimental work on these Mn-Fe-Si Laves phases that didn't surface in the literature search, please flag it — this is the kind of gap where overlooked data could be decisive.
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Experimental magnetic literature survey for Mn-Fe-Si C14 Laves phase validation