Rare-earth-free permanent magnet candidate system. WIP
493 on or near hull (< 150 meV/atom) entries for Fe-Ge-Co. Some dynamically unstable phases left in. Used Ggen system explorer.
Discovered 639 structures, 540 unique formulas
On this page
Metric | On Hull | Near | Far | Untested |
|---|---|---|---|---|
Hull | 27 | 477 | 63 | 72 |
Metric | Stable | Unstable | Untested |
|---|---|---|---|
Phonon | 466 | 68 | 105 |
→ 25 fully stable (hull + phonon), 400 near-hull stable
Crystal Systems
System | Count | Percentage |
|---|---|---|
triclinic | 297 | 46.5% |
monoclinic | 175 | 27.4% |
cubic | 45 | 7.0% |
trigonal | 40 | 6.3% |
orthorhombic | 33 | 5.2% |
tetragonal | 25 | 3.9% |
hexagonal | 24 | 3.8% |
Top Space Groups
Space Group | Number | Count | Percentage |
|---|---|---|---|
P1 | #1 | 271 | 42.4% |
Cm | #8 | 86 | 13.5% |
Pm | #6 | 51 | 8.0% |
Pm-3m | #221 | 31 | 4.9% |
P-1 | #2 | 26 | 4.1% |
Let's get into exploring some systems.
First one we're looking at. It's on the hull, P4/mmm.
Ggen exploration
Magnetic density: 0.146 µB / ų
MAE: 0.5612 MJ/m3
Bummer, not much MAE. Thankfully, we have plenty of other tetragonal and hexagonal entries to try!
5meV above the hull, P4/m space group.
5meV above the hull
Magnetic density: 0.177
MAE: 0.1919
7meV above the hull, P/42m.
7meV above the hull
Magnetic density: 0.122
MAE: 0.0648
13meV above the hull, P4/mmm.
13meV above the hull
Magnetic density: 0.141
MAE: 1.279 MJ/m3
Decent! Best MAE we've seen so far.
It seems like P4/mmm is the only space group we've seen so far that gives decent MAE. While we're still a ways a way, it's very clearly an order of magnitude greater than the other tetragonal systems we've tested here.
There were two systems within 150 meV / atom of the hull here, but neither of them were worth further testing as permanent magnets.
Found one worth testing, Fe4Ge, on the hull.
On the hull
Magnetic density: 0.165
MAE: 0.750
Surprisingly good, for how simple it is!
Seeing this success, going to explore just Fe-Ge binaries further!
It's strange, there is only one FeGe compound on the PD, and it's pretty high energy. The MP PD does have a stable FeGe, so I'll look at that and see why we missed it. I expect it's this z-index bug we had where we weren't searching all space groups because of sites with min multiplicity.
It's nice to see it in 2D now
It's pretty cool to see there is pretty clearly a significant energy barrier between the hull and the nearest entries (at least when Ge fraction > 20%).
Essentially, I've learned that we really should just be looking for stable P4/mmm plus P6/mmm, I4/mmm [and /mcm] based on what we know of other high MAE magnets.
Once I have more systems to compare against, Like Fe-Mn-Sn and Fe-Mn-Co, I think more patterns will emerge, and hopefully a couple good candidates!