Magnetic response of environmentally friendly prepared La3+ doped Li-Cu spinel ferrites

In this study, the Li_0.1Cu_0.5Fe_2.3–yLa_yO₄ (y = 0.0, 0.1, 0.2, 0.3, 0.4) spinel ferrites (SFs) were synthesized via self-ignition route, and their structural, morphological, compositional and magnetic properties were systematically analyzed. X-ray diffraction (XRD) analysis revealed a slight shift in the (311) diffraction peak position with increasing La³⁺ concentration, indicating lattice distortion. The crystallite size (D) decreased from 29.1 nm to 17.3 nm with doping, while lattice constant (a) and unit cell volume (V) exhibited a decreasing trend, confirming structural modifications due to La³⁺ addition in Li-Cu spinel lattice. Moreover, the particle size was also decreased from 42 nm to 22 nm with the substitution of La³⁺. Magnetic response demonstrated a significant reduction in saturation magnetization (M_S), from 60 emu/g to 23 emu/g, and coercivity (H_C), from 1331 Oe to 639 Oe, suggesting weakened magnetic interactions. The squareness ratio (SQ) increased, while the magnetocrystalline anisotropy constant (K) decreased, indicating enhanced magnetic softness. Furthermore, the microwave operating frequency (ω_m) was also reduced with La³⁺ doping, highlighting changes in dynamic magnetic behavior. These findings suggest that La³⁺ doping effectively tailors the structural and magnetic properties of Li-Cu SFs, making them potential candidates for tunable magnetic applications including recording media, memory devices, and transformer core applications.