#PhysicsFactlet
The lowest energy configuration for two magnetic dipoles is to align head-to-tail. But if we put the magnetic dipoles in a square array the ground state is composed of cross-like structures known as "microvortices".
[refs]
* https://journals.aps.org/prb/abstract/10.1103/PhysRevB.42.6574
* https://iopscience.iop.org/article/10.1088/1367-2630/5/1/368
@j_bertolotti In the thermo limit, is there a degeneracy under π/4 lattice rotations?
@andring @j_bertolotti I think so. Always, not only in the thermodynamic limit
@dduque @andring Plus (obviously) if you flip all dipoles you get an equivalent solution.