Reactively sputtered half-metallic Fe3O4 thin films at room temperature on polymethyl methacrylate: A perspective for flexible spintronics

For plastic spintronics, it has thus far been a challenge to develop a (magnetic nanostructures)/polymer heterostructure at low temperature due to the thermal sensitivity of polymers. In this context, half-metallic magnetite (Fe3O4) films of different thicknesses were coated on flexible polymethyl methacrylate (PMMA) substrates by reactive sputtering at 300 K. Grain size and thickness increased from similar to 10 nm to similar to 34 nm and 50 nm to 400 nm with an increase in the deposition time from 165 to 1335 s, respectively. Moreover, a sharp rise in grain size was observed when the thickness of the film reached 200 nm, and finally, saturation took place at 400 nm. X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and X-ray photoelectron spectroscopy (XPS) studies confirmed the absence of the gamma-Fe2O3 phase and thus the successful deposition of Fe3O4 thin films on the PMMA substrate. Parameters as such as Verwey transition (T-v) (similar to 125 K), saturation magnetization (M-s) (similar to 354 emu/cm(3)) and magnetoresistance (MR) ( - 8.6% under 60 KOe at 300 K) under H parallel to Film plane were obtained for Fe3O4/PMMA heterostructures with a film thickness of 200 nm. The resistivity (rho), T-v, M-s and MR were hardly affected on several bending tests, proving that Fe3O4/PMMA heterostructures are exciting materials for future flexible spintronics.