Enhancement in Magnetic and Magnetocaloric Properties of CoFe₂O₄ Nanofibers at Lower Temperatures

This research paper investigates new and first insights into the magnetic and magnetocaloric properties of one-dimensional (1D) cobalt ferrite CoFe₂O₄ (CFO) nanofibers (NFs) fabricated using a sol–gel-based electrospinning technique, focusing in particular on their behavior at low temperatures for specific applications. The microstructural, structural, magnetic, and magnetocaloric properties of the calcined CFO NFs were explored. The microstructure of the NFs, with an average diameter of 210 nm, was examined by scanning and transmission electron microscopy (SEM, TEM). The x-ray diffraction (XRD) of the CFO NFs showed a pure cubic close-packed (ccp) spinel crystalline structure with the Fd \(\overline{3}\) $\overline{3}$ m space group. The Raman spectroscopic studies further confirm the cubic inverse spinel phase. The magnetic properties were explored as a function of temperature, ranging from 10 K to 300 K, and ferromagnetic behavior was observed with the highest saturation magnetization of 75.87 emu/g and coercivity of 723 Oe at room temperature. The variation of the magnetic entropy was measured indirectly using the Maxwell approach with an increasing magnetic field. A maximum of \(\left| {\Delta S} \right|\) $\left|\mathrm{\Delta }S\right|$ = 1.71 J/K was reached around 32 K. At 180 K, the associated adiabatic temperature change, ΔT_max, was 0.93 K, with a large RCP value of 7.58 J/kg, which is reasonably high for the corresponding nanoparticles (NPs). This work suggests that 1D CFO NFs offer a promising route for the production of nanostructured magnetic materials, potentially impacting various electronic and electromagnetic device applications at low temperatures.