How to calculate the topological charge of the Bloch point?

[XBob]

Hello everyone, the normal topological charge of a skyrmion is either +1 or -1. However, during the simulation process, some topological defects often occur, such as the Bloch point. These topological defects become rather troublesome when calculating the topological charge they carry. Does mumax3 have a certain value that can reflect the magnitude of the topological charge, or is there a certain plugin that can calculate the topological charge of a certain section?I have read some literature. Could it also be possible that it was counted by the naked eye?

[Josh Lauzier]

Hi,

I don't think there is a way to do this within mumax. You could use ext_topologicalchargedensity.region() to get the charge density of a certain region, but you would need to do some postprocessing to integrate it to get back to the charge. In principle, ext_topologicalchargedensity.region().average might work ? I have not tested it compared to just ext_topologicalcharge. Unfortunately ext_topologicalcharge does not seem to have a .region() method.

You can try to do it via naked eye, but that wouldn't be rigorous, and would be fairly tedious. That might be fine for a quick sanity check but I wouldn't rely on eyeballing it.

Best,
Josh L.