Structural and magnetic susceptibility studies of samarium substituted magnesium–zinc ferrites

Polycrystalline soft ferrites Mg_1−x–Zn_x–Fe_2−y–Sm_y–O₄ (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0; y = 0.0, 0.05 and 0.1) were prepared by usual ceramic method. The samples were characterized by X-ray diffraction and IR techniques. Magnetic properties have been studied from magnetization and (a)–(c) susceptibility measurements. The XRD patterns of all the samples reveal the formation of single-phase cubic spinel. The IR spectra show two strong absorption bands in the frequency range 300–800 cm⁻¹. The magnetization measurements exhibit the Neel's collinear ferrimagnetic behavior for x ≤ 0.2 and suggest non-collinear Y–K (Yaffet–Kittel) type magnetic ordering for x ≥ 0.4. The samples with x ≥ 0.8 are paramagnetic at and above the room temperature. Variation of ac susceptibility with temperature exhibit the single domain structure (SD) with x = 0.0 and multi-domain (MD) structure with x ≥ 0.2 on substitution of Zn²⁺ content. On substitution of Sm³⁺ content, the samples exhibit SD for x = 0.0, MD for x = 0.2 and MD to SP transition for x ≥ 0.4.