Onset of magnetic order in multilayers of Fe and Ni on and embedded in fcc-Cu(100) substrates

We investigate magnetic correlations and local magnetic moments at finite temperatures in some Fe and Ni multilayers on and embedded in Cu(100). Our study is based on a mean-field theory of magnetic fluctuations for layered materials within the first-principles local spin-density functional theory. We find that although there is no significant local moments formation in the Ni layers, the Ni layers are not magnetically dead in the sense that they mediate magnetic interactions between Fe layers separated by Ni layers. The Curie temperature of FenNim/Cu(100) and NinFem/Cu(100) films is almost independent of the Ni layer thickness, however, in Fe1NinFe1/Cu(100) and Fe1CunFe1/Cu(100) films, the Curie temperature exhibits an interesting oscillatory behaviour as the spacer layer thickness is increased. We show that there is a connection between this behaviour and the spin-reorientation transition observed in some Ni films. In the Ni1FenNi1/Cu(100) and Cu1Fen/Cu(100) films we found that the nature and strength of the magnetic correlations depends upon the Fe layer thickness.