Influence of Co Substitution on the Diamagnetic to Soft Ferromagnetic Switching in BaTiO3 Nanoparticles for Spintronic Applications

We present our findings on the room temperature (RT) soft ferromagnetism (FM) of the sol-gel-prepared Co-doped barium titanate (BaTiO₃) nanoparticles with two distinct Co concentrations (0.25 mol% and 0.5 mol%), that is appropriate for spintronic applications as evidenced by experimental observations. X-ray diffraction investigation revealed that the produced samples, which had diameters less than 100 nm, belonged to the pseudo-cubic phase of the BaTiO₃ structure and did not exhibit any signs of the Co cluster or any other Co oxides. UV-visible absorption spectra demonstrate that the optical response is red shifted and the bandgap energy is lowered when Co is incorporated into the BaTiO₃ lattice. The inclusion of cobalt ions may have brought about a change in size or an increase in surface defects, as evidenced by the PL spectra, which show that the intensity of emission peaks changes as the dopant concentration increases. In the 0.25 mol% Co-doped BaTiO₃ sample, the FM behavior is clearly visible along with the paramagnetic (PM) phase at RT. Significantly, it becomes apparent that as the doping concentration is raised to 0.5 mol%, the saturation magnetization is reduced, and a pure phase of soft FM is obtained. This soft FM feature witnessed in 0.5 mol% doped BaTiO₃ with low coercivity (96.8 Oe) and low saturation magnetization (9.7 × 10⁻³ emu/g) is likely due to oxygen vacancies and could set out as a promising magnetic material for possible spintronic applications.