Low temperature field dependent magnetic study of the Zn0.5Co0.5Fe2O4 nanoparticles

This work is aimed to understand magnetic behavior at low temperature of nano particles of Zn_0.5Co_0.5Fe₂O₄ ferrite. The sample has been synthesized by using a Sol Gel method. Rietveld refinement of XRD data confirms the single-phase cubic spinel crystal structure with lattice constant a = 8.41 Å. The average crystallite size ~30 nm has been determined by Debye-Sherer formula. The field emission scanning electron microscopy micrographs show the spherical nature of nanoparticles and energy dispersive X-ray measurement confirms the elemental composition in the sample. Also, the Mapping of the sample has been performed which shows the appropriate distribution of elements in the sample. Magnetic measurements have also been performed in variable applied magnetic field (up to 5 T) and temperature (up to 2 K). The zero field cooled, field cooled curves have been measured under the applied magnetic field 50, 100 and 500Oe. The competition between thermal and magnetic energy has been studied in detail. In addition, the M-H loop has been measured at different temperatures i.e. 300 K, 200 K, 120 K, 100 K, 50 K and 5 K, by applying a variable external magnetic field up to ±5 T. The M-H loop is observed continuously decreasing with increasing temperature. The Bloch's law fitted in the saturation magnetization which gives M_o = 113.045emu/gm, T₀ = 547.45 K and ${\alpha }_B$ = 1.5. Also, the Kneller's law fitted in variable coercivity with respect to temperature which suggests that the blocking temperature ~360 K (i.e. above the room temperature). Furthermore, the dM/dH peak height is increasing with increasing temperature which indicates the good magnetic state of the sample.