I have been reading statements like "Ferromagnetic (anti-ferromagnetic) order can be detected or changed electrically using spin-transfer (spin-orbit) torque".
What is the exact meaning of changing (anti)ferromagnetic order here?
In the case of a ferromagnet, does it mean that we have switched a single up-spin to down-spin? Or we are talking about a bunch of spins flipping their spin? And what about an antiferromagnet in this sense?