Tuning the Magnetic Properties of FeCo Thin Films Through Magneto-Elastic Effect Induced by the Au Underlayer Thickness.

Tuning the magnetic properties of materials is a demand of several technologies, however, their control is still a challenge. In this work, we combined experimental and theoretical techniques to investigate the handling of magnetic properties of the FeCo thin films via the thickness-tuning of a gold film used as substrate. We growth the samples by the deposition of polycrystalline FeCo thin films on Au underlayer at room temperature by magnetron sputtering technique, demonstrating that the sub 20 nm thickness gold underlayers have a lattice parameter dependence on their thickness, inducing stresses up to 3 % in sub 5 nm FeCo thin film deposited over it. Thus, elastic-driven variations for the in-plane magnetic anisotropy energy (Ku ) up to 110 % are present in our experiments. Our results are supported by ab initio calculations, which are in excellent agreement with our experimental measurements. The handling mechanism here reported should be applied to other magnetic films deposited on different metallic underlayers, opening possibilities for large-scale fabrication of magnetic components to be used in future devices.