Tailoring electronic structure and magnetic anisotropy in spray-pyrolyzed NiFe2O4 thin films for spintronic applications

In this study, we examined how substrate temperature affects the structural, morphological, electronic, and magnetic properties of nickel ferrite (NiFe2O4) thin films synthesized via spray pyrolysis. We investigated the effect of substrate temperatures (300 °C, 325 °C, 350 °C, and 400 °C) on NiFe2O4 thin films. X-ray diffraction (XRD) analysis revealed an inverse spinel structure with enhanced crystallinity at lower substrate temperatures. We employed high-resolution scanning electron microscopy (HR-SEM) and energy-dispersive spectroscopy (EDS) to examine the surface morphology and elemental composition. We used vibrating sample magnetometry (VSM), X-ray absorption spectroscopy (XAS), and X-ray magnetic circular dichroism (XMCD) to study the magnetic and electronic behaviors at room temperature. VSM measurements revealed ferrimagnetic behavior with magnetic anisotropy. XAS and XMCD analyses revealed that Ni2+ ions occupy octahedral sites and are susceptible to structural defects, which lead to spin canting via spin-orbit coupling. Fe3+ ions were found in both tetrahedral and octahedral sites. The orbital magnetic moments were determined to be 0.112 ± 0.006 µB/ion for Ni and 0.2412 ± 0.0121 µB/ion for Fe. This was attributed to structural distortions and Fe 3d–O–2p hybridization. These results demonstrate the potential of NiFe2O4 thin films for use in spintronic devices.