Structure and Magnetism of Gd/MgO/Fe Superlattice-Based Nanosystems.

Gd/MgO/Fe superlattice-based nanostructures are an artificial ferromagnetic material, in which the exchange coupling of the magnetic moments of Fe layers through dielectric and rare-earth interlayers can create magnetic configurations atypical of the well-studied Fe/Cr and Fe/MgO/Fe systems. In this work, the structural features and magnetic properties of a series of Nb(20 nm)/[Gd(5 nm)/MgO(t nm)/Fe(5 nm)]_х6/Nb(5 nm) superlattices with MgO dielectric layers of different thicknesses (t = 0, 0.4, 0.8, and 1.2 nm) are examined. Using high-resolution X-ray reflectometry, the formation of a layered structure of superlattices with layer thicknesses close to nominal and a root-mean-square interface roughness of 10% of the total layer thickness is established. Using vibrating-sample magnetometry, a difference between the hysteresis loops of the magnetization of a sample without a MgO layer and samples with MgO layers of different thicknesses is revealed. It is found that the sample without dielectric layers has a significantly lower saturation magnetization. [ABSTRACT FROM AUTHOR]