The Impact of Fe2+ and Fe3+ Segregation on the Structural and Magnetic Properties of ZnO/Fe Multilayers Deposited via Sputtering: A Study Using EELS and EDS

Ferromagnetic (FM)-metal/oxide multilayers (MLs) play a central role in achieving highly efficient spin injection, crucial for determining the performance of spintronic devices. In this study, we investigate the microstructural and magnetic properties of [ZnO(5 nm)/Fe(t)](6) MLs (t =0.3, 0.4, 0.6, 0.8, and 1.0 nm) deposited on SiO2/Si substrates using magnetron sputtering. The characterization of the MLs was conducted through transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). X-ray diffraction (XRD), X-ray reflectivity (XRR), and TEM analyses reveal the presence of multiple crystallographic defects and macroscopic periodicity. Consistent chemical profiles across the ZnO/Fe MLs were identified through electron energy loss spectroscopy (EELS) and energy-dispersive X-ray spectroscopy (EDS) methods. The saturation magnetization of the ML with t = 0.3 nm is approximately five times lower than that of the ML with t =1 nm, and this discrepancy is attributed to indirect coupling between isolated Fe ions rather than the presence of clusters. These findings contribute to a comprehensive understanding of the microstructure and magnetic properties of the investigated ZnO/Fe MLs, offering insights for their potential applications in spintronics.