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ABSTRACT:Most of the articles devoted to giant magnetoresistance phenomenon take into account only the thickness variation of the spacer. Within this work, we study the magnetic behavior of the trilayer system Fe/Cr/Fe (0 0 1) after changing the thickness of the magnetic layers (Fe layers) and keeping the spacer constant (Cr layers). The calculations were done at the ab initio level by means of density functional theory, solving the Kohn-Sham equations with the full-potential linearized augmented plane wave method. These results show an oscillatory behavior of magnetic moment per atom as a function of the iron monolayers number.

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The ab initio full-potential linearized augmented plane-wave method explicitly designed for the slab geometry was employed to elucidate the physical origin of the layer potentials for the trilayers nFe/3Cr/nFe(001), where n is the number of Fe monolayers. The thickness of the transition-metal ferromagnet has been ranged from n = 1 up to n = 8 while the spacer thickness was fixed to 3 monolayers. The calculated potentials were inserted in the Fuchs-Sondheimer formalism in order to calculate the giant magnetoresistance (GMR) ratio. The predicted GMR ratio was compared with the experiment and the oscillatory behavior of the GMR as a function of the ferromagnetic layer thickness was discussed in the context of the layer potentials. The reported results confirm that the interface monolayers play a dominant role in the intrinsic GMR.

Electronic structure and magnetic properties of Fe N /Cr 3 /Fe N bcc (100) trilayers (N is the number of atomic layers) are studied on the basis of ab initio calculations performed within the framework of the density functional theory in the local spin density approximation, using the full-potential LAPW method in slab geometry. According to our calculations, the magnetic moment of a surface Fe layer increases monotonically from 2.45 B for N ϭ 1 to 2.92 B for N ϭ 3 and practically does not change at further increase of the Fe film thickness. However, the magnetic moment in the interface Fe layer changes nonmonotonically with the Fe film thickness increase and is close to the surface value at N ϭ 5 and 7.