Samarium-substituted CoFe₂O₄ nanoferrites: tailoring structural and magnetic properties for data storage and spintronic applications

Samarium-doped nanocrystalline cobalt ferrites with the chemical formula CoFe2-xSmxO4 were synthesized using the sol–gel autocombustion method. The as-prepared samples were characterized by powder X-ray diffraction to confirm the spinel ferrite phase, and the average crystallite size was 10–20 nm. X-ray peak profile analysis models revealed that a gradual decrease in the induced microstrain led to a small crystallite size with Sm3+ ions. The characteristic vibrational band of the CoFe2-xSmxO4 samples observed by Fourier transform infrared spectroscopy at 548.5 cm−1 confirmed the inverse spinel structure. The theoretical approach for UV-visible spectrophotometry data indicates the semiconductor characteristics. Micrographs of the sintered samples were obtained using a field-emission scanning electron microscope, and quantitative analysis was performed using an energy-dispersive X-ray spectrometer. The vibrating sample magnetometer at room temperature revealed a gradual decrease in the magnetic anisotropy constant (K) (4.82 × 104−2.0 × 104 J m−3), retentivity (Mr) (13.91−4.61 electromagnetic units (emu) g−1), squareness ratio (SQR) (0.29–0.18), saturation magnetization (Ms) (46.76–24.83 emu g−1) and the coercivity (Hc) (1012–789 oersted (Oe)), revealing a weak A–B interaction observed for the degradation of magnetic energy. Tolerance factor analysis showed well-defined values indicating a mixed-inverse spinel structure, revealing the effects of Sm3+ on the structural, morphological and magnetic properties of cobalt ferrites.