Multilayers CoFeNi/Cu with alternating layers of magnetic and nonmagnetic materials and a different number of ferromagnetic layers varying from 2 to 10 have been studied. It was found that with a thickness of ferromagnetic layers t = 3 nm, their optimal number, at which the maximum magnetoresistance is observed in the nanostructure, is three. A further increase in the number of ferromagnetic layers leads to a sharp decrease in magnetoresistance, which is due to a change in the initial antiferromagnetic ordering to an ordering close to ferromagnetic. The reverse change of the magnetic ordering from ferromagnetic to antiferromagnetic in nanostructures with a fixed number of layers occurs with a decrease in the thickness of the CoFeNi layers, which is accompanied by a multiple increase in magnetoresistance.
Milyaev et al. (2025) studied this question.