Magnetic anisotropy in sputtered Ga-rich Fe-Ga thin films

Fe-Ga alloys have appeared as promising materials because they are rare-earth free systems with a large magnetostriction and a low coercivity. The magnetostriction shows two maxima in two Ga ranges, around 20 at.% and 28 at.%, being higher in the Ga-rich range. The strong influence of processing on the magnetostrictive properties of bulk alloys has been reported [Acta Materialia56, 4536 (2008)] highlighting the relevance of a precise control of the growth method. Reducing the dimensions, e.g. thin films, can further modify the magnetic properties but it is required to develop miniaturized devices. In this work, we present our recent investigations about sputtered Ga-rich Fe-Ga alloys. We have explored how the flow regime of the sputtering technique can be used to tune the in-plane magnetic anisotropy [PRB93, 214408 (2016)]. Furthermore, we have also studied how the anisotropy is also dependent on the layer thickness [JALCOM745, 413 (2018)]. Our structural (XRD and XAS) and magnetic (VSM and MOKE) characterizations indicate that both growth parameters and thickness have an influence on the structural phases present in the Fe-Ga alloys. The increase of ordered phases together with a preferential order of the Ga-pairs seem to play a role on the enhancement of the anisotropy. Therefore, this experimental work sheds light on the correlation between structural and magnetic properties and how to exploit them to tune the magnetic properties in Fe-Ga thin films.