That is actually quite fascinating and curious.
There will have to be some new textbooks written!
Thanks for posting it!
~Easy
Actually, those textbooks have already been written - on iron-based superconductors displaying spontaneous static magnetic fields with broken time-reversal symmetry.
They came hot off the presses in January of 2020, and will appear in all better bookstores sometime in December of 2019.
I remember finding a dusty old copy of one during a book drive my local library was holding in June of 1998.
Regards,