A film with this property pins the top film of permalloy (“perm-alloy”) in valve-like devices used as hard-drive read heads. Doping the insulator LaMnO3 with calcium or strontium causes it to [emphasize] stop exhibiting this phenomenon and become highly conductive. The first conclusive evidence of a material exhibiting this phenomenon came from Clifford Shull and Samuel Smart’s neutron diffraction experiment. In an archetypal example of this phenomenon, it arises because d electrons partially occupy the antibonding orbital of a Mn–O–Mn chain, and thus the manganese (-5[1])ions can interact across oxygen via superexchange. Uniquely, chromium (-5[1])exhibits this phenomenon at room temperature. In (10[1])materials exhibiting this phenomenon, susceptibility (-5[1])increases (-5[1])with (-5[1])temperature up to the (10[1])Néel (“NAY-el”) temperature. (10[3]-5[2])For 10 points, (10[2])name this (10[1])phenomenon (-5[1])in which neighboring spins (-5[1])point in opposite directions. (10[4]-5[1])■END■ (10[4]0[7])