Magnetic polarization of the Pd spacer and interlayer magnetic couplings in Fe/Pd (001) superlattices: First principles calculations

This paper is devoted to a theoretical study of the magnetic properties of Fe/Pd superlattices. We mostly focus our attention on the determination of both the interlayer magnetic couplings (IMC) and the magnetic-moment distributions as a function of the Pd spacer’s thickness. We use an ab initio method (augmented spherical wave) to determine self-consistently the electronic structure, the magnetic-moment distributions, and the total energies for the considered systems. We consider two model structures for the Pd spacers (1) a fct structure for which the Pd atoms keep their bulk atomic volume and (2) a fcc structure for which the Pd atomic volume is expanded. For the first structure, the magnetic polarization in the palladium spacer is limited mostly to the first three monolayers near the Fe-Pd interfaces and the IMC are similar to the ones obtained for nonmagnetic spacers. The IMC decrease rapidly with an oscillating behavior. On the contrary, for the second atomic structure, the whole Pd spacer is polarized with a moment of about 0.15${\mathrm{\mu }}_{\mathit{B}}$/atom for n≤14 (n being the number of Pd atomic layers) and the IMC are ferromagnetic in a large range of Pd thicknesses. We present a detailed study of (i) ${\mathrm{Fe}}_3$ ${\mathrm{Pd}}_1$ superlattices whose ground state is shown to be antiferromagnetic and (ii) the polarization induced in the Pd spacer in relation with the current theoretical models.