Magnetic, Electronic Structure And Interface Study Of Fe/MgO/Fe Multilayer
Jitendra Pal Singh, Sanjeev Gautam, Braj Bhusan Singh, S. Chaudhary, D. Kabiraj, D. Kanjilal, K. H. Chae, R. Kotnala, Jenn-Min Lee, Jin-Ming Chen, K. Asokan
Keywords: Magnetic multilayers; e-beam evaporation; X-ray absorption spectroscopy; X-ray reflectometry.
MgO based magnetic tunnel junctions (MTJs) exhibit high tunneling magnetoresistance (TMR) and have potential applications in magnetic random access memories. This study addresses the role of interface in the Fe/MgO/Fe based MTJs. For present investigation, Fe/MgO/Fe multilayer stack on Si substrates is grown by electron beam evaporation method and has been investigated for structural, magnetic and electronic properties. All the layers in the stack were of polycrystalline in nature as evidenced from X-ray diffraction studies and the magnetic measurements show the perpendicular magnetic anisotropy. Results from near edge X-ray absorption spectra at Fe L-edges measured by total electron yield mode and X-ray reflectometry indicate the formation of FeOx at the Fe/MgO interface. These are associated with hybridization of Fe (3d)-O(2p) levels at Fe/MgO interface in the stack and thickness of layers in the stacks. Absence of magnetic de-coupling between top and bottom ferromagnetic layers has been attributed to interface roughness, oxidation at Fe/MgO interface. This study highlights the role of interface and oxidation that need to be considered for improving the TMR for devices.