Amplitude and phase of the oscillatory exchange coupling between Fe-Co-Ni alloy layers across a Cu spacer layer

The influence of alloying in ferromagnetic layers on the amplitudes and phases of the oscillations of exchange coupling across Cu layers is studied from first principles. The phases of oscillations vary monotonically with the average number of valence electrons in the alloyed layers and are insensitive to the type of atom from which the layers are formed. We show that in accordance with an RKKY-like description, the exchange coupling energies can be expressed in terms of complex amplitudes characterizing the magnetic subsystems.