Modeling the sublattice magnetizations for the layered bcc nanojunction …Fe[Fe1−cCoc]ℓFe……Fe[Fe1−cCoc]ℓFe… systems

• Salient magnetic properties of complex nanostructured alloy ferromagnetic junctions.
• Ising spin effective field theory (EFT) used to compute magnetic exchange.
• Computed sublattice magnetizations of the Fe and Co sites on the nanostructures.
• Effective magnetic moments per site deduced by EFT and mean field theory (MFT).
• Appropriate magnetic modeling at the interfaces of the nanostructured ferromagnetic junctions.

Ferromagnetic nanojunctions …Fe[Fe1−cCoc]ℓFe……Fe[Fe1−cCoc]ℓFe…, with ℓ is the number of layers which constitute the nanojunction, based on Fe/Co alloy are considered for the first time in this work. We model the salient magnetic properties of the layered ferromagnetic nanostructures between magnetically ordered iron leads. The effective field theory (EFT) Ising spin method is used to compute reliable Jav exchange values for the VCA Fe/Co alloy materials in comparison with experimental data and compared to existing DFT calculated exchange interactions. The new set of exchange interaction values between pairs of nearest neighbors atom in the alloy are deduced and agree with previous known measurement of lattice constant for this alloy. Using the combined EFT and mean field theory (MFT) spin methods, the sublattice magnetizations of the Fe and Co sites on the individual bcc basal planes of the layered nanostructures, are calculated and analyzed. The sublattice magnetizations, effective magnetic moments per site, and the possible ferromagnetic order of the layers [Fe1−cCoc]ℓ[Fe1−cCoc]ℓ on the individual bcc atomic planes of the embedded nanostructures for all temperatures and in particular for TcFe≤T≤Tα→γ are presented as a function of temperature and thicknesses of the layered ferromagnetic nanostructures, for different stable concentrations c=0.25, 0.5 and 0.75. In the absence of first principles calculations for these basic physical variables for the layered nanostructures between iron leads, the combined EFT and MFT approach yields the only available information for them at present in the absence of a possible Curie temperature for these alloys. These variables are necessary for certain spin dynamic computations, as for the ballistic magnon transport across embedded nanojunctions in magnonics. The model is general, and may applied directly to other composite magnetic elements and embedded nanostructures.