Critical behavior and magnetocaloric properties of (0.5)Co0.7Zn0.3Fe2O4 / (0.5)La0.67Sr0.23K0.10MnO3 nanocomposite

Abstract

This research investigates the microstructural and magnetocaloric characteristics, critical behavior, and type of magnetic interaction in Co_0.7Zn_0.3Fe₂O₄ (CZFO)/La_0.67Sr_0.23K_0.10MnO₃ (LSKMO) nanocomposite sample, obtained by mixing the nanoparticles of spinel ferrite CZFO and manganite LSKMO in 1:1 ratio. The Rietveld refined X-ray diffraction analysis confirms the presence of both phases without any interdiffusion, whereas a distribution of irregular and polyhedral grains is observed using field emission scanning electron microscopy. Magnetic measurements confirm a second-order magnetic transition with a $T_C$ value of 358 K. The values of change in maximum magnetic entropy and relative cooling power of this sample under a 1 T magnetic field are found to be 0.49 Jkg⁻¹K⁻¹ and 23.7 Jkg^-1, respectively. The change in specific heat ($\Delta C_P)$ alters from negative to positive around $T_C$, with estimated values of ${\Delta C}_P^{\max }$ and ${\Delta C}_P^{\min }$ as $4.04$ and $3.20$ Jkg⁻¹K⁻¹, respectively. In order to study the critical behavior of the sample near $T_C$, the critical exponents ($\alpha$, $\beta$, $\gamma$, and $\delta$) were obtained through modified Arrott plots, critical isotherm scaling, Widom scaling relation, and renormalization group theory. Our study suggests that the $3D$ Heisenberg model, characterized by short-range spin-spin interaction, is the most appropriate model to understand critical behavior. The present results can be helpful for selecting a novel approach to choosing the materials for magneto-refrigerant devices operating close to room temperature.